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Glossary/Explanation of Math Terms


Sometimes we forget the words we learned in different subjects when we were in elementary school, and sometimes teachers use different words than those we learned. This glossary contains information about common math terms your child may be learning about in school. The terms and math operations listed below have been adapted from two websites. Go to these sites to find more information about words and topics not listed here.



above, below  The kite is above the house. The clothes are below the butterfly.

+  =

Next to, beside. These lines are adjacent.

after, before,

The bear is before the elephant. The monkey is after the elephant. The elephant is between the bear and the monkey.

afternoon, morning, evening 



Is the half of the day from midnight to midday. What we call morning. ? INCLUDEPICTURE "http://www.mathsisfun.com/measure/images/am-pm.gif" \* MERGEFORMATINET 
Is the half of the day from midnight to midday. What we call morning.

It comes from the Latin "Ante Meridiem".

alike These shapes are alike in color. These shapes are not alike by the number of sides.

bar graph
bottom, middle, totop
Cardinal number
Cardinal numbers (or cardinals) are numbers that say how many of something there are, such as one, two, three, four, five.?Answers the question "How Many?"??Example: there are five coins.
Cardinal numbers (or cardinals) are numbers that say how many of something there are, such as one, two, three, four, five.

Answers the question "How Many?"

Example: there are five coins.

A 2-dimensional shape made by drawing a curve that is always the same distance from a center.

clock An instrument used to measure or indicate time.
Clockwise; counterclockwise
Counterclockwise is moving in the direction of the hands on a clock.?The opposite direction is called counterclockwise. ?
Counterclockwise is moving in the direction of the hands on a clock.?The opposite direction is called counterclockwise. ?
Counterclockwise is moving in the direction of the hands on a clock.?The opposite direction is called counterclockwi
Counterclockwise is moving in the direction of the hands on a clock.?The opposite direction is called counterclockwise. 

Taps and most screws and bolts are closed by turning clockwise. 

cone A solid (3-dimensional) object that has a circular base and one corner.

cube  A cube is a box-shaped solid object that has six identical square faces.

cylinder A cylinder is a solid object with:
* two identical flat circular or elliptical ends?
* and one curved side. 

cup A unit of measurement. One cup = 8 ounces.

difference Difference is the amount between two objects 
9 – 3 = 6      the difference is 6 

digit A symbol used for numbers. 
The digits are 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 are digits.
9 is a one digit number, and 19 has two digits, 219 has three digits.

dime 10¢   or   10 cents 

1 dime = 10 pennies

divide 6 items
6 ÷ 2 = 3      
2 2 2

dollar 1 dollar = 100 pennies 

doubles twice as many or as much; two times as many or as much

edge A line that is the intersection of two planes (sides)

equal Equal means same as. 
The stacks are equal.

25 is equal to 25.

estimate To guess roughly about how many or how much.

the estimate is about ten buttons 

even numbers Even numbers can be divided exactly by 2, and can make pairs. 
The last digit will be 0, 2, 4, 6, 8.

face Any of the individual surfaces of a solid object.
Example: this tetrahedron has 4 faces (there is one face you can't see)

factor Factors are the numbers you multiply together to get another number:

Example: 2 and 3 are factors of 6, because 2 x 3 = 6.

foot 1 foot = 12  HYPERLINK "Javascript:%20new_definition(link)" inches. 

A fraction is a part of a whole.

The number written on the bottom (the denominator) tells you how many parts the whole is divided into, and the top number (the numerator) tells how many you have.

formula Numbers and symbols that show how to work something out.

Example: The formula for finding the volume of a box is "V = w × d × h"?(V stands for volume, w for width, d for depth and h for height. ?If w=4, d=5 and h=10, then V = 4×5×10 = 200.)

finite Has an end. Could be measured, or given a value.
There are a finite number of people at this beach.
There are also a finite number of grains of sand at this beach.
The length of the beach is also finite.

frequency How often something happens during a period of time.

Example: This is a heartbeat with a frequency of 78 beats per minute.

gram A measure of weight. 

A paper clip weighs about 1 gram

greater than more than > 

63 is greater than 29.
63 > 29

gradient How steep a straight line is.?

In this example the gradient is 3/5 = 0.6 

graph A diagram of values, usually shown as lines or bars.

gross Before any deductions. 

Example: "gross income" means before tax and expenses.?
Also means twelve dozen (144)

half One of two equal parts of a whole

Example: my friend and I shared a piece of fruit. We each had half. 

half dollar 1 half dollar = 50 pennies

    50¢             50 cents
half hourhalf hour

There are 30 minutes in a half hour; between 4:00 and 4:30 is a half hour.

height The vertical distance from top to bottom

hexagon A 6-sided polygon (a flat shape with straight sides).

horizontal Going side-to-side, like the horizon.

Parallel to the horizon.
(Up-down is called vertical)

hour A period of time equal to 1/24 (a twenty-fourth) of a day.

1 Day = 24 Hours?
1 Hour = 60 minutes.
Example: The amount of time between 9:00 and 5:00 is eight hours.


hundreth One part in a hundred equal parts

hypotenuse The side opposite the right angle in a right-angled triangle


Improper fraction An improper fraction is a fraction where the numerator (the top number) is greater than or equal to the denominator (the bottom number). In other words, it is top-heavy.

Example: 5/3 (five thirds) and 9/8 (nine eighths) are improper fractions?Improper fractions are NOT bad.

inch An inch is a measure of length. There are 12 inches in a foot, and 36 inches in a yard.

The abbreviation is in., or sometimes the double quote mark: 
One inch is exactly 2.54 centimeters.

Example: this ruler measures up to 12 inches (or up to 30 centimeters on the bottom scale).

increase Make something bigger (in size or quantity).

inequality An inequality says that two values are not equal. 
a ≠ b says that a is not equal to b 
There are other special symbols that show in what way things are not equal 

not equal

less than
er than

less than or equal to

greater than or equal to

a < b says that a is less than b?
a > b says that a is greater than b
a ≤ b means that a is less than or equal to b
a ≥ b means that a is greater than or equal to b.

integer number with no fractional part. 

Includes the counting numbers {1,2,3,…}, zero {0}, and the negative of the counting numbers {-1, -2, -3, …}

You can write them down like this: {…, -3, -2, -1, 0, 1, 2, 3, …}

To cross over (have some common point)

The red and blue lines intersect.

kilometer A Metric measure of distance. Equal to 1,000 meters.
The abbreviation is km.

Example: it takes about 10 minutes to walk 1 km
1 kilometer = 0.6 miles approximately.?

Example: 60 miles is about 100 kilometers

less than < shows that one number is smaller than another

29 < 63
29 is less than 63

Length Distance. How far from end to end.

Example: the length of this guitar is about 1 meter

line A long thin mark made by a pen, pencil, etc. 

In geometry a line:
* is straight (no curves),
* has no thickness, and ?
* extends in both directions without end (infinitely).

If it does have ends it would be called a "Line Segment".

line graph A graph that uses points connected by lines to show how something changes in value (as time goes by, or as something else happens).

lowest common denominator The smallest number that can be used for all denominators (the bottom number) of 2 or more fractions

Example: the Lowest Common Denominator of 1/2 and 2/3 is 6, because they can be written as 3/6 and 4/6. Also called least common denominator.

liter 1 liter is a little more than 1 quart

maximum The largest value.

The maximum of {14, 4, 16, 12} is 16

meter 1 meter is a measurement than equals one hundred centimeters

mean The mean is the average of the numbers.

It is easy to calculate: Just add up all the numbers, then divide by how many numbers there are. Example: what is the mean of 2, 7 and 9?

Add the numbers: 2 + 7 + 9 = 18

Divide by how many numbers (i.e. we added 3 numbers): 18 ÷ 3 = 6?
So the Mean is 6

measure To find a number that shows the size or amount of something usually, the number is in reference to some standard measurement, such as a meter or kilogram.

median The middle number (in a sorted list of numbers). Half the numbers in the list are less, and half the numbers are greater. To find the Median, place the numbers you are given in value order and find the middle number.

Example: find the Median of {12, 3 and 5}. Put them in order: {3, 5, 12}, the middle number is 5, so the median is 5.

If there are two middle numbers (as happens when there are an even amount of numbers) then average those two numbers. 

Example: find the Median of {12, 3, 5 and 2}. Put them in order: {2, 3, 5, 12}, the middle numbers are 3 and 5, the average of 3 and 5 is 4, so the median is 4.

midpoint The middle of, the point halfway along.


milli A prefix meaning one-thousandth (1/1,000)

millimeter A Metric unit of length, used for small lengths.

The abbreviation is mm. There are 1,000 mm in one meter.

The small lines on this ruler show mm. The ruler can measure up to 300 mm (the "30" means 30 centimeters which equals 300 millimeters)

million A million is a thousand thousands (1,000,000).

minimum The smallest value.

The minimum of {14, 4, 16, 12} is 4.

minuend The number that is to be subtracted from.

minuend - subtrahend = difference

Example: in 8 - 3 = 5, 8 is the minuend.

minute A unit of time equal to 60 seconds.

There are 60 minutes in an hour. 

mode The number which appears most often in a set of numbers. 

Example: in {6, 3, 9, 6, 6, 5, 9, 3} the Mode is 6 (it occurs most often).

month One of the twelve parts of the year: 

January, February, March, April, May, June, July, August, September, October. November, December

multiple The result of multiplying by a whole number

Example: 4 × 5 = 20?
20 is a multiple of 4 and also of 5.
These are some of the multiples of 3: 12, 15, 18, 21

multiplication The basic idea of multiplication is repeated addition.

For example: 5 × 3 = 5 + 5 + 5 = 15

But as well as multiplying by whole numbers, you can also multiply by fractions or decimals.

For example 5 × 3½ = 5 + 5 + 5 + (half of 5) = 17.5

multiplication sentence The story of what is multiplied and what the product is.

4 x 3 = 12

multiplication tables table that shows you the results of multiplying two numbers. One number is along a row, the other down a column, and the results are shown where a row and column meet.

Example: 6 multiplied by 7 is 42

natural number The whole numbers from 1 upwards: 1, 2, 3, and so on ...

Or from 0 upwards in some fields of mathematics: 0, 1, 2, 3 and so on ...

No negative numbers and no fractions.


negative number Less than zero.

(Positive means more than zero. Zero is neither negative nor positive.)

A negative number is written with a minus sign in front

Example: -5 is negative five


nickel nickel

5¢   or   5 cents 

1 nickel = 5 pennies

not equal to There is a special symbol used to show that one number is not equal to another. It is ≠

a ≠ b says that a is not equal to b

Example: 4 ≠ 9 shows that 4 is not equal 9

number line number line 

number pattern A list of numbers that follow a certain sequence or pattern.

Example One: 1, 4, 7, 10, 13, 16, 19, … starts at 1 and jumps 3 every time.

Example Twp: 2, 4, 8, 16, 32, … doubles each time

numeral A symbol or name that stands for a number.

Examples: 3, 49 and twelve are all numerals

numerator The top number in a fraction.

Shows how many parts we have.

oblong A rectangle that is not a square. (all sides not equal)

octogon An 8-sided polygon (a flat shape with straight sides).

odd number Any integer that cannot be divided exactly by 2. 

The last digit will be 1, 3, 5, 7 or 9

Example: -3, 1, 7 and 35 are all odd numbers

order of operations The rules of which calculation comes first in an expression

Do everything inside parentheses first: ()
then do exponents: x2
then do “multiplies” and “divides” from left to right
lastly do the “adds” and “subtracts” from left to right

Example: 5 × (3 + 4) - 2 × 8 = 5 × 7 - 2 × 8 = 35 - 16 = 19

ordering Putting things into their correct place following some rule.

Example: put the numbers {3, 12, 5, 2, 9} into order from highest to lowest. Start at the highest (12) and go down: {12, 9, 5, 3, 2} 

Putting the shapes in order by number of sides.

ordinal number A number that tells the position of something in a list.

1st, 2nd, 3rd, 4th, 5th etc.

ounce A unit of weight. There are 16 ounces in a pound.

A slice of bread weighs about one ounce.

oval An oval or ovoid is any curve that looks like an egg or an ellipse. 

It is not a precise term and there are many curves that get called "oval".

pair Two together. Often with something in common.

Example: {12,7} is a pair of numbers

parallel Always the same distance apart and never touching.

parallelogram Opposite sides are parallel and equal in length, and opposite angles are equal (angles "a" are the same, and angles "b" are the same)

NOTE: Squares, Rectangles and Rhombuses are all Parallelograms!

parentheses Parentheses or "round brackets" are the familiar ( ) symbols used in pairs to group things together.

Example: (3 + 2) x (6 - 4) = 5 x 2 = 10

The Parentheses group 3 and 2 together, and 6 and 4 together.

pattern Things that are arranged following a rule or rules.

Example, red, blue green, red blue, green…

Example: there is a pattern in these numbers: 2, 7, 12, 17, 22, … The rule is "start at 2 and add 5 each time"

pentagon A 5-sided polygon (a flat shape with straight sides).

percent Percent means parts per 100. The symbol is %

Example: 25% means 25 per 100

(25% of this box is grey)

perimeter The distance around a two-dimensional shape. 

Example: the perimeter of this rectangle is 3+7+3+7 = 20

The perimeter of a circle is called the circumference.

perpendicular At right angles (90°) to

pi The ratio of a circle's circumference to its diameter.

Approximately equal to 3.14159265358979323846…

pie chart A pie chart is a circular chart divided into sectors; each sector shows the relative size of each value.

place value The value of where the digit is in the number, such as units, tens, hundreds, etc. 

In 352, the place value of the 5 is "tens"

plane A plane is a flat surface with no thickness.

It extends forever.

plot To draw on a graph or map.

Here we have plotted the point (12,5).

plus Another word for add. The symbol is +

Example: 30 cents plus 20 cents equals 50 cents.

PM Is the half of the day from Midday to Midnight.

What we call afternoon and evening.

It comes from the Latin "Post Meridiem" for "after midday".

point An exact location. It has no size, only position.

Here we have marked the location of three points: (-2,-1), (0,0) and (3,2)

polygon A plane shape (two-dimensional) with straight sides.

Examples: triangles, rectangles and pentagons.

(Note: a circle is not a polygon because it has a curved side)

polyhedron A solid with flat faces (from Greek poly- meaning "many" and -edron meaning "face").

Example: pyramids and prisms

Each flat surface (or "face") is a polygon.

population The whole group from which a sample is taken. 

position Where something is located (often in relation to something else).

Example: here are some statements about position in this photo:
* the dog is in front of the woman, ?
* the boats are on the water?
* the mountains are in the distance 

positive Greater than zero.
(Negative means less than zero. Zero is neither negative nor positive.)

Example: 5 is a positive number, or positive five.

power The power of a number shows you how many times to use the number in a multiplication. It is written as a small number to the right and above the base number. Another name for power is index or exponent.?

In this example: 102 = 10 × 10 = 100

prime factor A factor that is a prime number. One of the prime numbers that, when multiplied, give the original number. 

The prime factors of 15 are 3 and 5 (3x5=15), and 3 and 5 are prime numbers).

prime number A Prime Number can be divided evenly only by 1, or itself. (In other words, it's factors are only 1 or itself)

Example: 13 can only be divided evenly by 1 or 13, so it is a prime number.
If it is not a Prime Number it is called a Composite Number.

Example: 14 can be divided evenly by 1, 2, 7 and 14 so it is a composite number.

probability Probability is the chance that something will happen - how likely it is that some event will happen.

Sometimes you can measure a probability with a number: "10% chance of rain", or you can use words such as impossible, unlikely, possible, even chance, likely and certain. ?

Example: "It is unlikely to rain tomorrow".

problem A question that needs a solution.

In mathematics some problems use words:
"John was traveling at 20 km per hour for half an hour. How far did he travel?"
And some use equations: "Solve x+5=22".

Product The answer when two or more numbers are multiplied together.

property An attribute or character that something has. Such as color, height, weight, etc.

Some properties of this shape are:
Its color is gray, it has 5 sides, it is regular (all sides and angles are equal)

Protractor An instrument used in measuring or drawing angles.

Pyramid A solid object where:
* The base is a polygon (a straight-sided shape)
* The sides are triangles which meet at the top (the apex).

It is a polyhedron.

This is a square pyramid, but there are also triangular pyramids, pentagonal pyramids, and so on.

Quantity How much there is of something. 

Example: What is the quantity of rice?
You could say "a handful", or you could even count them "1262" !

One of four equal parts
Written as 1/4
This circle has been cut into quarters, and one quarter is darker.
Also a coin – 25¢ 4 quarters = $1.00

The answer after you divide one number by another
dividend ÷ divisor = quotient?
Example: in 12 ÷ 3 = 4, 4 is the quotient 

Radius The distance from the center to the edge of a circle
It is half of the circle's diameter.


Random Without order. Not able to be predicted. Happening by chance.?

However, there will be an overall structure, tending to be within a certain range.? 

These two dice will give random results, but always between 2 and 12.

Another Example: the values {2.18, 2.17, 2.23, 1.82, 1.87, 2.02, 1.83} are random, but are close to 2.

Random Sample A selection that is chosen randomly (purely by chance, with no predictability)

Example: if you wanted to take a random sample of water from a river, you could have a map of the river and choose a spot blindfolded then work out how to get there!

Range The difference between the lowest and highest values.

In {4, 6, 9, 3, 7} the lowest value is 3, and the highest is 9, so the range is 9-3 = 6.

Ratio A ratio shows the relative sizes of two or more values.

Ratios can be shown in different ways. Using the ":" to separate example values, or as a single number by dividing one value by the total.

Example: if there is 1 boy and 3 girls you could write the ratio as:
1:3 (for every one boy there are 3 girls)
1/4 are boys and 3/4 are girls
0.25 are boys (by dividing 1 by 4)
25% are boys (0.25 as a percentage) 

Rational number Any number that can be made by dividing one integer by another. The word comes from "ratio".

1/2 is a rational number (1 divided by 2, or the ratio of 1 to 2)
0.75 is a rational number (3/4)
1 is a rational number (1/1)
2 is a rational number (2/1)
2.12 is a rational number (212/100)
-6.6 is a rational number (-66/10)

Ray A ray is a line with a start point but no end point (it goes to infinity)

Real number The type of number we normally use, such as 1, 15.82, -0.1, 3/4, etc…

Positive or negative, large or small, whole numbers or decimal numbers are all Real Numbers. 

Reciprocal To get the reciprocal of a number, just divide 1 by the number

Example: the reciprocal of 2 is 1/2 (half)
Every number has a reciprocal except 0 (1/0 is undefined)
It is shown as 1/x, or x-1
If you multiply a number by its reciprocal you get 1 

Rectangle A rectangle is a four-sided polygon (a flat shape with straight sides) where every angle is a right angle (90°). 

Also, opposite sides are parallel and of equal length.?
Example: A square is a special type of rectangle.

Reduce To make smaller

Example: if you reduce the heat it will get cooler

Remainder The amount left over after division (as happens if one number can't be divided exactly by the other)

Example: 19 cannot be divided exactly by 5. The closest you can get without going over is 3 x 5 = 15, which is 4 less than 19.

So the answer of 19 ÷ 5 is 3 with a remainder of 4.

Rhombus A four-sided shape where all sides have equal length. 

Also opposite sides are parallel and opposite angles are equal.?It is a type of parallelogram. 

Right Angle A right angle is an angle which is equal to 90°, one quarter of a full revolution.

Roman numerals How ancient Romans used to write numbers.

I, V, X, L, C, D, M are the symbols used.

Example: 1984 = MCMLXXXIV

We still use them today in special places, like numbering important events such as the Olympic Games, and sometimes on clocks and books. 

Root Where a function equals zero.

In this example, -2 and 2 are the roots of the function x2 - 4?But sometimes "root" is used as a quick way of saying "square root" 

Rotation A circular movement. 

There is a central point that stays fixed and everything else moves around that point in a circle. A circular movement. 

Rounding Rounding means reducing the digits in a number while trying to keep it's value similar.

The result is less accurate, but easier to use.

This is the common method:
* Decide which is the last digit to keep
* Increase it by 1 if the next digit is 5 or more (this is called rounding up)
* Leave it the same if the next digit is less than 5 (this is called rounding down)

Example: 243 rounded to the nearest ten is 240 (because 3 is less than 5) 

Row Things lying side-by-side. Objects, People, Numbers, etc in a horizontal line.

Example: a row of numbers: 5, 7, 11, 20, 22
(Columns go up-down. Rows go left-right.)

Here is a row of apples:

Ruler A ruler is something used to measure distances or to rule straight lines.

This ruler is marked in cm along the top and inches along the bottom. 

Sample A selection taken from a larger group (the "population") so that you can examine it to find out something about the larger group.

Scale The ratio of the length in a drawing (or model) to the length of the real thing

Example: In the drawing of the horse,   "1 inch" would be "10 inches" in the real world.
Second The basic unit of time. 

There are 60 seconds in 1 minute and 3,600 seconds in an hour.

The “Second hand” is the longer hand that moves the fastest; it shows the seconds.

One second is approximately the time of one heartbeat when you are resting. You can get a rough count of seconds by saying "One cat-and-dog, Two cat-and-dog, Three cat-and-dog, … " etc., or you may prefer "a-thousand-and One, a-thousand-and Two, a-thousand-and Three , … " 

Segment The area of a circle made by a line and an arc.

Semicircle Half a circle

Sequence A list of numbers or objects which are in a special order.

Example: 2, 4, 8, 16, 32, 64, 128, 256, … is a geometric sequence (each number is 2 times the number before it)

Set A collection of "things" (objects or numbers, etc).

Each member is called an element of the set. 

There should only be one of each member (all members are unique).

Example: {1,2,3,4} is the set of counting numbers less than 5

Shape The form of an object - how it is laid out in space? Common shapes are:

Circles, squares, triangles, … (two dimensional)?
Spheres, cubes, pyramids, … (three dimensional) 

Sign Used with a name, it means a symbol used instead of words, such as the percent sign.

Used on its own, it means negative or positive.
Example: what sign is the number? Is it negative? 

Similar In Geometry, two shapes are Similar if the only difference is size (and possibly the need to turn or flip one around). 

These two shapes are Similar (one is smaller and flipped over, but otherwise same)

Sine In a right angled triangle, the sine of an angle is:

The abbreviation is sin

Skip counting
Where you count forwards or backwards by a number other than 1?Example: Skip counting by 3 is: 3, 6, 9, 12, …
Where you count forwards or backwards by a number other than 1
Example: Skip counting by 3 is: 3, 6, 9, 12, …
Where you count forwards or backwards by a number other than 1?Example: Skip counting by 3 is: 3, 6, 9, 12, …

Slope How steep a straight line is.

In this example the slope is 3/5 = 0.6

Solid A three dimensional object: width, depth and height

Examples include, spheres, cubes, pyramids and cylinders.

Sort To arrange or group in a special way (such as by size, type or alphabetically).

Sphere A 3-dimensional object shaped like a ball.

Every point on the surface is the same distance from the center.

Square A 4-sided polygon (a flat shape with straight sides) where all sides have equal length and every angle is a right angle (90°)

Square numbers To multiply a number by itself.

Example: 4 × 4 = 16

Square Root The square root of a number is that special value that, when multiplied by itself, gives the number.

Example: 4 × 4 = 16, so the square root of 16 is 4.

The symbol is √?
Example: √36 = 6 (because 6 x 6 = 36) 

Substitution In Algebra "Substitution" means putting numbers where the letters are:
Example 1: If x=5, then what is x + 10/x ?
Put "5" where "x" is: 5 + 10/5 = 7

To take one number away from another.?If you have 5 apples and you subtract 2, you will be left with 3.? INCLUDEPICTURE "http://www.mathsisfun.com/numbers/images/subtraction.gif" \* MERGEFORMATINET ?The symbol of subtraction is -?Example: 5 - 2 = 3
To take one number away from another.
To take one number away from another.?If you have 5 apples and you subtract 2, you will be left with 3.? INCLUDEPICTURE "http://www.mathsisfun.com/numbers/images/subtraction.gif" \* MERGEFORMATINET ?The symbol of subtraction is -?Example: 5 - 2 = 3
If you have 5 apples and you subtract 2, you will be left with 3.

The symbol of subtraction is -?  
Example: 5 - 2 = 3

Successive One after the other.?
Monday, Tuesday and Wednesday are successive days.?
5 and 7 are successive odd numbers.

Sum The result of adding two or more numbers.

Example: 9 is the sum of 2, 4 and 3, because 2 + 4 + 3 = 9.
Supplementary Angles Two Angles are Supplementary if they add up to 180 degrees.?
They don't have to be together to be supplementary, just so long as the total is 180 degrees.

60° and 120° are supplementary angles.?
93° and 87° are supplementary angles.

Surface Area The total area of the surface of a three-dimensional object

Example: the surface area of a cube is 6 × (Edge Length)2 

Symbol A pattern or image used instead of words.?
Example: "+" is the symbol for "plus"?
This is the "recycle" symbol. 

Symmetry Symmetry is when one shape becomes exactly like another if you flip, slide or turn it.

The simplest type of Symmetry is "Reflection" (or "Mirror") Symmetry, as shown in this picture of a dog.

Table Numbers or quantities arranged in rows and columns

This is a table of what sport people play at a school. 

Tangent A line that just touches a curve at one point, without cutting across it.

Example: the tangent of a circle.

Temperature How hot or cold a thing is.
Temperature is measured using a thermometer, usually in Celsius or Fahrenheit scale.

This thermometer shows that the temperature is about 28 degrees Celsius.

Tenth One part in ten equal parts.?
A tenth of these 100 blocks is highlighted. 

Example: one tenth of 50 is 5

Term In Algebra a term is either a single number or a variable, or numbers and variables multiplied together.

Three-dimensional An object that has height, width and depth, like any object in the real world.

Example: your body is three-dimensional
Times Another word for multiply, the symbol is x

Example: 3 times 5 is 15, or 3 x 5 = 15

Times Tables Another word for multiplication tables.

Timetable A table of information showing when things will happen.

Examples: this is part of a bus timetable. 

Total The result of adding some numbers?
Example: In 12 + 4 + 6 = 22, 22 is the total. 

Trapezoid A trapezoid (UK: trapezium) is a quadrilateral with one pair of opposite sides parallel.

It is not a parallelogram because only one pair of sides is parallel.

It is called a regular trapezoid if the sides that aren't parallel are equal in length and both angles coming from a parallel side are equal (shown on the right). 

Triangle A 3-sided polygon (a flat shape with straight sides). 

Triple To make something three times as large (multiply by three)
Triple 6 is 18 (because 3 × 6 = 18)

Twice Two times as many.
8 is twice 4

Two-dimensional A shape that only has two dimensions (such as width and height) and no thickness.

Squares, Circles, Triangles, etc are two dimensional objects
Unequal Not equal
The symbol is ≠
Example: 7 ≠ 5 (7 is not equal to 5) 

Units How many ones. How many single items.

Used to show the "ones" place value (units, tens, hundreds, etc)
Example: 27 has two tens and 7 units.

Unit of Measurement A quantity used as a standard of measurement.

Example: Units of time are second, minute, hour, day, week, month, year and decade.

Value Money how much something is worth.

Mathematics the result or 'output' of a calculation.?
Example: 3 × 4 gives the value of 12.

Variable A symbol for a number we don't know yet. It is usually a letter like x or y.

Example: in x + 2 = 6, x is the variable?If it is not a variable it is called a Constant.

Vertex/Vertices A point where two or more straight lines meet. Corner.

Example: a corner of a polygon (2D) or of a polyhedron (3D) as shown.?The plural of vertex is "vertices".

Vertical In an up-down position. Upright.

Example: trees grow in a vertical direction.?
(Side-to-side is called horizontal)

Volume The amount of 3-dimensional space an object occupies. Capacity.

For this example the volume is 4×5×10 = 200 units3

A time period of 7 days.?Example: Wednesday, Thursday, Friday, Saturday, Sunday, Monday and Tuesday together make a week.
A time period of 7 days.
Example: Wednesday, Thursday, Friday, Saturday, Sunday, Monday and Tuesday together make a week.
Weekdays are Monday through Friday, and weekends are Saturday and Sunday.

Weight "Heaviness". The downward force caused by gravity on an object.

Whole All of something. Complete.

Whole number The numbers {0, 1, 2, 3, …} etc.?
There is no fractional or decimal part. And no negatives.?
Example: 5, 49 and 980 are all whole numbers.

Width The distance from side to side.

Example: the width of this door is 80 cm.

X The letter "x" is often used in algebra to mean a value that is not yet known. It is called an "unknown" or a "variable".

But it doesn't have to be "x", it could be "y", "w" or any letter or symbol.

X Axis The line on a graph that runs horizontally (left-right) through zero.

It is used as a reference line so you can measure from it.

X Coordinate The horizontal value in a pair of coordinates. How far along the point is.
Always written first in an ordered pair of coordinates (x,y), such as (12,5).

In this example, the value "12" is the X Coordinate.

Y Axis The line on a graph that runs vertically (up-down) through zero.

It is used as a reference line so you can measure from it.

Y Coordinate The vertical value in a pair of coordinates. How far up or down the point is. 
Always written second in an ordered pair of coordinates (x,y) such as (12,5).

Also called "Ordinate"

Y Intercept Where a straight line crosses the Y axis of a graph.

Year A period of time in which the Earth makes a complete revolution around the sun.

There are 365 days in a normal year and 366 days in a leap year.?The first day of the year is 1st January, and the last day is 31st December.

Zero The whole number between -1 and 1, with the symbol 0

Shows that there is no amount.
Example: 6 - 6 = 0 (the difference between six and six is zero)?Useful as a "place-holder" so that you can write a numeral properly.?Example: 502 (five hundred and two) could be mistaken for 52 (fifty two) without the zero in the tens place.