Math Dictionary
Simple, clear definitions for every math term you need to know. From basic concepts to advanced terminology.
A
C
Coefficient
A coefficient is the numerical factor that multiplies a variable in an algebraic expression. It tells you how many of that variable you have.
Constant
A constant is a fixed value that does not change. In algebra, constants are numbers without variables attached. In an equation, constants remain the same regardless of variable values.
D
E
Equation
An equation is a mathematical statement showing that two expressions are equal, connected by an equals sign (=). Equations can be solved to find the value of unknown variables.
Exponent
An exponent tells you how many times to multiply a number by itself. It appears as a small raised number to the right of the base.
Expression
A mathematical expression is a combination of numbers, variables, and operations (like +, −, ×, ÷) that represents a value. Unlike equations, expressions do NOT have an equals sign.
F
Fraction
A fraction represents a part of a whole or a division of quantities. It consists of a numerator (top number) and a denominator (bottom number) separated by a line.
Function
A function is a rule that assigns exactly one output to each input. Every input (x-value) maps to exactly one output (y-value). Written as f(x), this notation shows the function name and input.
H
I
Inequality
An inequality is a mathematical statement comparing two expressions using inequality symbols: < (less than), > (greater than), ≤ (less than or equal to), ≥ (greater than or equal to), or ≠ (not equal to).
Integer
An integer is any whole number (positive, negative, or zero) without fractions or decimals. The set of integers is: {..., −3, −2, −1, 0, 1, 2, 3, ...}
Intercept
An intercept is where a line or curve crosses an axis. The y-intercept is where it crosses the y-axis (where x = 0). The x-intercept is where it crosses the x-axis (where y = 0).
M
Mean
The mean is the average of a set of numbers. Calculate it by adding all values together and dividing by the count of values. It represents the "central" value of a data set.
Median
The median is the middle value when numbers are arranged in order. If there's an even count of numbers, the median is the average of the two middle values.
Mode
The mode is the value that appears most frequently in a data set. A set can have no mode (all values appear once), one mode, or multiple modes (bimodal, multimodal).
N
P
Perpendicular
Perpendicular means meeting or crossing at a right angle (90°). Two perpendicular lines form an "L" shape.
Prime Number
A prime number is a natural number greater than 1 that has exactly two factors: 1 and itself. It cannot be evenly divided by any other number.
Probability
Probability measures how likely an event is to occur. It's calculated as the number of favorable outcomes divided by the total number of possible outcomes. Probability ranges from 0 (impossible) to 1 (certain).
Q
R
S
V
Variable
A variable is a symbol (usually a letter like x, y, or z) that represents an unknown or changeable value in a mathematical expression or equation.
Volume
Volume measures the amount of space inside a three-dimensional object. It is measured in cubic units (cm³, m³, in³, ft³). Volume tells you how much a container can hold.
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