Math Study Glossary

A quick study of mathematics terminology can help you know where you need to shore up your own understanding of key concepts. There are some great online resources to help any student of math. Please report any issues. here. Enjoy!

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The abacus is a calculating tool once used for manually performing arithmetic processes. Also called a counting frame.
absolute value
How far a number is from zero on a number line. The positive value of a number. For example, for 10, this number is 10. For -10, this number is also 10.
acute angle
An angle which is greater than 0 and less than 90 degrees.
acute triangle
A triangle in which each of the angles measures less than 90 degrees.
additive identity
The number zero is called the additive identity because when adding zero to any number, the sum is that number.
additive inverse
The additive inverse of any number "n" is the number that gives zero when it's added to n. For example, for 10, this is -10.
adjacent angles
Two angles that share both a vertex and a side.
A precise rule or set of rules which define how to solve a specific problem.
A shape formed by two rays sharing a common endpoint or two lines that intersect.
A portion of the circumference of a circle.
A two-dimensional quantity expressing the size of a shape or figure.
associative property of addition
An observation that grouping or associating numbers in differing orders results in the same sum during an addition operation. For example, this can be expressed mathematically in the following equation: (a + b) + c = a + (b + c)
associative property of multiplication
An observation that grouping or associating numbers in differing orders results in the same product during a multiplication operation. For example, this can be expressed mathematically in the following equation: (a * b) * c = a * (b * c)
A number that typifies a set of numbers of which it is a function. Also known as the mean. For example, this can be calculated as n1 + n2 + n3 = total / 3 (where 3 is the quantity of numbers that were added together).
axis of symmetry
Any line that passes through a shape in such a way that the parts on each side are a reflection of each other.
The bottom of a triangle or other shape.
To cut or divide into two parts, especially two equal parts.
Box-and-Whisker plot
An illustration showing the distribution of a set of data along a number line, dividing the data into four parts using the median and quartiles.
Cartesian coordinates
A system in mathematics, which specifies each point in a plane uniquely by a pair of numerical coordinates, which are the signed distances from the point to two fixed perpendicular directed lines, measured in the same unit of length. Also called rectangular coordinate system.
central angle
An angle whose vertex is the center of a circle.
A line segment that connects two points on a curve.
A set of points on a surface which are a certain distance from a central point.
The distance around a circle.
A constant number which serves as a measure of some property or characteristic.
Points lying on the same line.
A collection of things, in which the order does not matter.
common factor
A factor of two or more numbers.
common multiple
A multiple of two or more numbers.
commutative property of addition
An observation that reordering the numbers being added results in the same summation. For example, this can be illustrated mathematically in the following expression: a + b = b + a.
commutative property of multiplication
An observation that reordering the numbers being multiplied results in the same product. For example, this can be illustrated mathematically using the following expression: a * b = b * a.
complementary angles
Two angles whose sum is 90 degrees.
composite number
An integer that is divisible without remainder by at least one positive integer other than itself or 1.
A three-dimensional figure with one vertex and a circular base.
Figures or angles having identical size and shape.
A value that does not change.
coordinate plane
The plane determined by a horizontal number line, called the x-axis, and a vertical number line, called the y-axis, intersecting at a point called the origin. Each point in the coordinate plane can be specified by an ordered pair of numbers.
Points that lie within the same plane.
counting numbers
The natural numbers, or the numbers used to count.
counting principle
If a first event has n outcomes and a second event has m outcomes, then the first event followed by the second event has n times m outcomes.
cross product
A product found by multiplying the numerator of one fraction by the denominator of another fraction and the denominator of the first fraction by the numerator of the second.
A solid figure with six square faces.
A three-dimensional figure having two parallel bases that are congruent circles.
Information that is gathered.
decimal number
The numbers in the base 10 number system, having one or more places to the right of a decimal point.
A unit of measure of an angle.
The bottom part of a fraction.
dependent events
Two events in which the outcome of the second is influenced by the outcome of the first.
The line segment connecting two nonadjacent vertices in a polygon.
The line segment joining two points on a circle and passing through the center of the circle.
The result of subtracting two numbers.
A single element from a numbering system. For example, 0, 1, 2, 3 are each digits. In the number 1024, 1, 0, 2 and 4 are each digits.
distributive property
An observation illustrated by the following expression: a(b + c) = ab + ac
The number in an equation being divided. For example given the following expression, a / b = c, a is the dividend.
In a / b = c, b is the divisor.
The set of all points in a plane such that the sum of the distances to two fixed points is a constant.
A mathematical statement that says that two expressions have the same value; any number sentence with an =.
equilateral triangle
A triangle that has three equal sides.
equivalent equations
Two equations whose solutions are the same.
equivalent fractions
Fractions that reduce to the same number.
error of measurement
The difference between an approximate measurement and the actual measure taken.
To substitute number values into an expression.
even number
A natural number that is divisible by 2.
In probability, a set of outcomes.
A number that indicates the operation of repeated multiplication.
One of two or more expressions that are multiplied together to get a product.
To break a number into its factors.
A flat surface of a three-dimensional figure.
A equation that states a rule or a fact.
A number used to name a part of a group or a whole. The number below the bar is the denominator, and the number above the bar is the numerator.
The number of times a particular item appears in a data set.
frequency table
A data listing which also lists the frequencies of the data.
A type of drawing used to represent data.
greatest common factor (GCF)
The largest number that divides two or more numbers evenly.
A line with zero slope.
The side opposite the right angle in a right triangle.
identity property of addition
The sum of any number and 0 is that number.
identity property of multiplication
The product of 1 and any number is that number.
improper fraction
A fraction with a numerator that is greater than the denominator.
independent events
Two events in which the outcome of the second is not affected by the outcome of the first.
A mathematical expression which shows that two quantities are not equal.
A limitless quantity.
inscribed angle
An angle placed inside a circle with its vertex on the circle and whose sides contain chords of the circle.
inscribed polygon
A polygon placed inside a circle so that each vertex of the polygon touches the circle.
The set of numbers containing zero, the natural numbers, and all the negatives of the natural numbers.
The x-intercept of a line or curve is the point where it crosses the x-axis, and the y- intercept of a line or curve is the point where it crosses the y-axis.
intercepted arc
The arc of a circle within an inscribed angle.
A method for estimating values that lie between two known values.
intersecting lines
Lines that have one and only one point in common.
Opposite. -5 is the additive inverse of 5, because their sum is zero. 1/3 is the multiplicative inverse of 3, because their product is 1.
inverse operations
Two operations that have the opposite effect, such as addition and subtraction.
irrational number
A number that cannot be expressed as the ratio of two integers.
isosceles triangle
A triangle with at least two equal sides.
least common denominator
The smallest multiple of the denominators of two or more fractions.
least common multiple
The smallest nonzero number that is a multiple of two or more numbers.
like fractions
Fractions that have the same denominator.
A straight set of points that extends into infinity in both directions.
line of symmetry
Line that divides a geometric figure into two congruent portions.
line segment
Two points on a line, and all the points between those two points.
A path of points.
The study of sound reasoning.
lowest terms
Simplest form; when the GCF of the numerator and the denominator of a fraction is 1.
In a data set, the sum of all the data points, divided by the number of data points; average.
The middle number in a data set when the data are put in order; a type of average.
A point on a line segment that divides the segment into two congruent segments.
mixed number
A number written as a whole number and a fraction.
A type of average; the number (or numbers) that occurs most frequently in a set of data.
A multiple of a number is the product of that number and any other whole number. Zero is a multiple of every number.
multiplicative identity
The number 1 is the multiplicative identity because multiplying 1 times any number gives that number.
multiplicative inverse
The reciprocal of a number.
mutually exclusive events
Two or more events that cannot occur at the same time.
natural numbers
The counting numbers.
negative number
A real number that is less than zero.
number line
A line on which every point represents a real number.
The top part of a fraction.
obtuse angle
An angle whose measure is greater than 90 degrees.
obtuse triangle
A triangle with an obtuse angle.
A polygon with 8 sides.
odd number
A whole number that is not divisible by 2.
Addition, subtraction, multiplication, and division are the basic arithmetic operations.
Two numbers that lie the same distance from 0 on the number line but in opposite directions.
ordered pair
Set of two numbers in which the order has an agreed-upon meaning, such as the Cartesian coordinates (x, y), where the first coordinate represents the horizontal position, and the second coordinate represents the vertical position.
The point (0, 0) on a coordinate plane, where the x-axis and the y-axis intersect.
In probability, a possible result of an experiment.
Two lines are parallel if they are in the same plane and never intersect.
A quadrilateral with opposite sides parallel.
A five-sided polygon.
A fraction, or ratio, in which the denominator is assumed to be 100. The symbol % is used for percent.
The sum of the lengths of the sides of a polygon.
A way to arrange things in which order is important.
Two lines are perpendicular if the angle between them is 90 degrees.
The ratio of the circumference of a circle to its diameter.
A flat surface that stretches into infinity.
A location in a plane or in space, having no dimensions.
A closed plane figure made up of several line segments that are joined together.
A three-dimensional solid that is bounded by plane polygons.
positive number
A real number greater than zero.
A number that indicates the operation of repeated multiplication.
prime number
A number whose only factors are itself and 1.
For an experiment, the total number of successful events divided by the total number of possible events.
The result of two numbers being multiplied together.
proper fraction
A fraction whose numerator is less than its denominator.
An equation of fractions in the form: a/b = c/d
A device for measuring angles.
A three-dimensional figure that has a polygon for its base and whose faces are triangles having a common vertex.
Pythagorean Theorem
The theorem that relates the three sides of a right triangle: a(squared) + b(squared) = c(squared)
One of the quarters of the plane of the Cartesian coordinate system
A polygon with 4 sides.
The answer to a division problem.
The distance from the center to a point on a circle; the line segment from the center to a point on a circle.
In statistics, the difference between the largest and the smallest numbers in a data set.
A ratio that compares different kinds of units.
A pair of numbers that compares different types of units.
rational number
A number that can be expressed as the ratio of two integers.
part of a line, with one endpoint, and extending to infinity in one direction.
real numbers
The combined set of rational numbers and irrational numbers.
The number which, when multiplied times a particular fraction, gives a result of 1.
A quadrilateral with four 90-degree angles.
A transformation resulting from a flip.
regular polygon
A polygon in which all the angles are equal and all of the sides are equal.
repeating decimal
A decimal in which the digits endlessly repeat a pattern.
A parallelogram with four equal sides.
right angle
An angle whose measure is 90 degrees.
right triangle
A triangle that contains a right angle.
The root of an equation is the same as the solution to the equation.
A transformation in which a figure is rotated through a given angle, about a point.
sample space
For an experiment, the sample space includes all the possible outcomes.
scale drawing
A drawing that is a reduction or enlargement of the original.
scalene triangle
A triangle with three unequal sides.
A graph with points plotted on a coordinate plane.
scientific notation
A method for writing extremely large or small numbers compactly in which the number is shown as the product of two factors.
A well-defined group of objects.
Two polygons are similar if their corresponding sides are proportional.
Reducing to lowest terms.
skew lines
Lines that are not in the same plane and that do not intersect.
The steepness of a line expressed as a ratio, using any two points on the line.
The value of a variable that makes an equation true.
A three-dimensional figure with all points in space a fixed distance from a given point, called the center.
A quadrilateral with four equal sides and four 90 degree angles.
square root
The square root of x is the number that, when multiplied by itself, gives the number, x.
The science of collecting, organizing, and analyzing data.
stem and leaf plot
A technique for organizing data for comparison.
straight angle
An angle that measures 180 degrees.
supplementary angles
Two angles are supplementary if their sum is 180 degrees.
surface area
For a three-dimensional figure, the sum of the areas of all the faces.
surface normal
A vector that is perpendicular to that surface.
terminating decimal
A fraction whose decimal representation contains a finite number of digits.
A transformation, or change in position, resulting from a slide with no turn.
A change in the position, shape, or size of a geometric figure.
A line that intersects two other lines.
A quadrilateral that has exactly two sides parallel.
tree diagram
A diagram that shows outcomes of an experiment.
A three-sided polygon.
unit price
Price per unit of measure.
A letter used to represent a number value in an expression or an equation.
The point on an angle where the two sides intersect.
vertical angles
A pair of opposite angles that is formed by intersecting lines.
A measurement of space, or capacity.
whole numbers
The set of numbers that includes zero and all of the natural numbers.
The horizontal axis in a Cartesian coordinate plane.
The value of x at the point where a line or curve crosses the x-axis.
The vertical axis in a Cartesian coordinate system.
The value of y at the point where a curve crosses the y-axis.
The additive identity; the number that, when added to another number n, gives n.
zero property of multiplication
The product of zero and any number is zero.

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