Math Glossary

A working glossary of math vocabulary. Each term gets a one-sentence working definition and, where we cover it in depth, a link to the article that goes further.

A

Absolute Value — The distance of a number from zero, regardless of sign. |−5| = 5, |3| = 3.

Algebra — Math that uses letters or symbols to represent unknown numbers. Lets you write rules that apply to any number, not just one specific number.

Arithmetic — The math of numbers and the basic operations (addition, subtraction, multiplication, division). The foundation of everything else.

Area — The measure of how much surface is enclosed by a 2D shape. Measured in square units (m², cm², in²).

Average (mean) — The sum of a list of numbers divided by how many numbers there are.

Axis — A reference line on a graph or coordinate system. Usually an x-axis (horizontal) and a y-axis (vertical).

C

Calculus — The math of change and accumulation. Differential calculus measures how fast something changes; integral calculus measures totals over time.

Coefficient — The numerical part of a term in algebra. In 5x, the coefficient is 5.

Combinatorics — The math of counting how many ways things can happen. How many possible orderings of 10 books, how many different pizza topping combinations, etc.

Coordinate — A pair (or triple) of numbers that locates a point in space.

D

Decimal — A number written using powers of ten. Includes a decimal point separating the whole-number part from the fractional part.

Denominator — The bottom number in a fraction. The total number of equal parts being considered.

Derivative — In calculus, the rate at which a function is changing at a given point. The slope of the tangent line.

Distribution — In statistics, how often each value or range of values occurs in a dataset.

Divisor — The number you divide by.

E

Equation — A mathematical statement that two expressions are equal. 2 + 3 = 5.

Exponent — The small raised number that tells you how many times to multiply the base by itself. In 2³ = 8, the exponent is 3.

Expression — A combination of numbers, operations, and (in algebra) variables. Unlike an equation, an expression doesn't include an equals sign.

F

Factor — A number that divides evenly into another number. 3 and 4 are both factors of 12.

Formula — A standardized equation that lets you calculate one quantity from others. Area of a rectangle = length × width.

Fraction — A number that represents part of a whole, written as numerator over denominator. ½, ¾, ⅗.

Function — A rule that pairs each input with exactly one output. Often written f(x) = something.

G

Geometry — The math of shapes, sizes, angles, areas, and volumes.

Graph — A visual representation of data or a function — points, lines, bars, or curves plotted on axes.

Greatest Common Factor (GCF) — The largest number that divides evenly into two or more given numbers.

I

Inequality — A statement that two expressions are NOT equal, or that one is greater (or less) than the other. Uses signs like <, >, ≤, ≥.

Integer — A whole number, positive, negative, or zero. (No fractions or decimals.)

Integral — In calculus, the accumulated total of a quantity over a range. The opposite operation of derivative.

L

Least Common Multiple (LCM) — The smallest number that two or more given numbers all divide into evenly.

Linear — Related to a straight line. A linear equation produces a straight-line graph.

Logarithm — The inverse of exponentiation. The logarithm base 10 of 1000 is 3, because 10³ = 1000.

M

Mean — Another word for average — the sum divided by the count.

Median — The middle value of a sorted dataset.

Mode — The most frequently occurring value in a dataset.

Multiplication — Repeated addition. 4 × 3 means "four threes" — 3 + 3 + 3 + 3 = 12. → Multiplication Quiz Printable Sheet.

N

Natural Number — Any positive whole number: 1, 2, 3, 4, …

Numerator — The top number in a fraction. The number of parts you have.

O

Operation — A mathematical action. The four basic operations are addition, subtraction, multiplication, and division.

Order of Operations — The agreed-upon sequence for evaluating a math expression: Parentheses, Exponents, Multiplication and Division (left to right), Addition and Subtraction (left to right). The PEMDAS rule.

P

Percent — A fraction with 100 as the denominator, written with the % sign. 25% means 25 out of 100.

Perimeter — The total distance around a 2D shape.

Pi (π) — The ratio of a circle's circumference to its diameter. Approximately 3.14159…

Polynomial — An algebraic expression with multiple terms, like 3x² + 2x − 5.

Prime Number — A number greater than 1 that has no factors other than 1 and itself. 2, 3, 5, 7, 11, 13, …

Probability — The math of how likely an event is to happen. Expressed as a number between 0 (impossible) and 1 (certain), or as a percentage.

Proportion — A statement that two ratios are equal. → Intro to Ratios covers proportions in depth.

Q

Quadratic — An expression with a variable raised to the second power. Quadratic equations (ax² + bx + c = 0) have famous solutions via the quadratic formula.

Quotient — The answer to a division problem.

R

Ratio — A comparison of two quantities, often written a:b. → Intro to Ratios.

Rational Number — Any number that can be expressed as a fraction (one integer over another).

Real Number — Any number on the number line — integers, fractions, decimals, irrational numbers like π and √2.

Reciprocal — The result of flipping a fraction upside down. The reciprocal of ¾ is 4/3.

S

Set — A collection of distinct objects.

Sequence — An ordered list of numbers. 2, 4, 6, 8, … is an arithmetic sequence.

Slope — How steep a line is. Rise divided by run.

Square Root — A number that, when multiplied by itself, gives the original number. √9 = 3.

Standard Deviation — In statistics, how spread out a dataset is around its mean.

Statistics — The math of summarizing and reasoning about data.

T

Term — A single number, variable, or product of numbers and variables in an algebraic expression.

Trigonometry — The math of triangles, especially the relationships between angles and side lengths.

V

Variable — A symbol (usually a letter) that stands for an unknown or changing quantity.

Volume — The measure of how much 3D space something occupies. Measured in cubic units.

W

Whole Number — A non-negative integer: 0, 1, 2, 3, …

Word Problem — A math problem presented in everyday language rather than equations. The strategy-and-translation problem most students find hardest. → Breaking Down Word Problems.

See Also

• What Is Math? — Big-picture orientation.
• Branches of Math — Field-by-field guide.
• Math resources hub — All articles.
• Worksheets — Printable practice.