FIRST IN MATH - Glossary of Math Terms
FIRST IN MATH - Glosario de términos matemáticos




Acute Angle: An angle with a measure less than 90º

Addend: Any number that is being added.

Adjacent angles:  Two angles that share a common side and vertex, but don’t overlap.

Algorithm: A step-by-step solution to a problem.

Analog Time: Time displayed on a timepiece having hour and minute hands.

Area: The measure, in square units, of the inside of a plane figure.

Array: A rectangular arrangement of objects in equal rows or columns.

Attribute: A property of an object. (Example: color or shape)

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Bar Graph : A graph that uses bars to show data.

Benchmark fractions: Commonly used fractions, often for estimation.

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Capacity: The amount that something can hold.

Chord: A line segment whose endpoints are on a circle.

Circumference: The distance around a circle.

Combination: A group of items. Placing these items in a different order does not create a new combination.

Complementary Angles:  Two angles whose measurements add to 90°.

Compose (Composition): Put together, join.

Composite number: A whole number having more than two factors.

Cone: A solid figure that has a circular base and one vertex.

Congruent: Having the same size and shape. EXAMPLE - Congruent angles have the same measure; congruent segments have the same length.

Cube: (noun) A rectangular solid having six congruent, square faces.

Cube: (verb) To raise a quantity or number to the third power. (x)(x)(x)

Cylinder: A three-dimensional figure with two circular bases, which are parallel and congruent.

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Decompose (Decomposition): Take apart, separate.

Denominator: The bottom number of a fraction. 

Diameter: A line segment that has endpoints on a circle and passes through the center of the circle.

Difference: The answer in a subtraction problem. EXAMPLE: 8 - 3 = 5; 5 is the difference.

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Edge: The line segment where two faces of a solid figure meet.

Equation: A statement that two mathematical expressions are equal.

Equilateral triangle: A triangle with all three sides of equal length. The angles of an equilateral triangle are always 60°

Endpoint: Either of two points marking the end of a line segment.

Equivalent: Having the same value.

Estimate: A close guess of the actual amount.

Expanded form: Writing out a number to show the value of each digit. (Also called Expanded notation)

Expanded notation: A way to write numbers that shows the value of each digit
(EXAMPLE: 4372 = 4000+300+70+2).

Exponent: Written as a small number to the right and above the base number. An exponent shows how many times a number is to be multiplied by itself.

Expression: A variable, or any combination of numbers, variables, and symbols that represents a mathematical relationship (EXAMPLE: 24 x 2 + 5 or 4a – 9).

Exterior Angles: The angle formed by any side of a polygon and the extension of its adjacent side.

Even number: Any integer that can be divided evenly by 2.

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Face: A plane figure that serves as one side of a solid figure.

Fact family: A set of related addition and subtraction, or multiplication and division equations using the same numbers (EXAMPLE: 6+9=15, 15-9=6, 9+6=15, 15-6=9).

Factor: A whole number that divides evenly into another whole number (EXAMPLE: 1, 3, 5, and 15 are factors of 15).

Factor pairs: Any two numbers being multiplied together that give you a chosen number. (Example: Some factor pairs of 16 are: 8x2, 4x4, and 16x1)

Function: A relation in which every input value has a unique output value.

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Glide reflection: A combination of two transformations: a reflection over a line followed by a translation in the same direction as the line.


Greatest common factor (GCF): The largest factor that 2 or more numbers have in common.

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Heptagon/Septagon:  A polygon with 7 sides. Each interior angle in a regular heptagon/septagon has a measure of 128.57°.

Hexagon:  A polygon with 6 sides. Each interior angle in a regular hexagon has a measure of 120°.

Histogram: A bar graph in which the labels for the bars are numerical intervals.

Hypotenuse: The longest side of a right triangle (which is also the side opposite the right angle).

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Improper fraction: A fraction where the numerator (the top number) is greater than or equal to the denominator (the bottom number).

Inequality: A mathematical sentence that contains a symbol that shows the terms on either side of the symbol are unequal (EXAMPLE: 3+4>6).

Integer: Any of the natural numbers, the negatives of these numbers, or zero. A whole number (a number that is not a fraction).

Interior Angles: An angle inside a polygon.

Intersecting lines: Lines that cross.

Interval: The distance between two points or events.

Inverse operation: The operation that reverses the effect of another operation. (Example: Addition and subtraction are inverse operations)

Irrational Number: a number that cannot be written as a simple fraction - it's decimal goes on forever without repeating. It is called "irrational" because it cannot be written as a ratio (or fraction).

Isosceles triangle: A triangle with two equal sides.

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Least common denominator (LCD): The least common multiple of the denominators in two or more fractions.

Least common multiple (LCM): The smallest number, other than zero, that is a common multiple of two or more numbers.

Leg (of a right triangle): Either of the two sides that form the right angle in a right triangle.

Line: A straight path extending in both directions with no endpoints.

Line of symmetry: A line that divides a figure into two halves that are mirror images of each other.

Line plot: A graph showing the frequency of data on a number line.

Line segment: A part of a line with two endpoints.

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Mass: A measure of how much matter is in an object. (Commonly measured as weight)

Maximum: The largest value possible.

Mean (average): The number found by dividing the sum of a set of numbers by the number of addends.

Median:  The middle number in an ordered set of data, or the average of the two middle numbers when the set has two middle numbers.

Minimum: The smallest value possible.

Mixed number: A whole number and a fraction written as one number.

Mode: The number(s) that occurs most often in a set of data.

Multiples: The product of a given whole number and another whole number (EXAMPLE: multiples of 4 are 4, 8, 12, 16….).

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Nonagon: A polygon with 9 sides. Each interior angle in a regular nonagon has a measure of 140°.

Number line: A line with numbers placed in their correct position.

Numerator: The top number of a fraction.

Number sentence: An equation or inequality with numbers.

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Obtuse angle: An angle with a measure more than 90º.

Octagon: A polygon with 8 sides. Each interior angle in a regular octagon has a measure of 135°.

Odd number: Any integer that CANNOT be divided evenly by 2.

Ordered pair: A pair of numbers used to locate a point on a coordinate grid. The first number tells how far to move horizontally, and the second number tells how far to move vertically.

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Parallel lines: Lines that never intersect and are always the same distance apart.

Parallelogram: A quadrilateral whose opposite sides are parallel and congruent.

Pentagon: A polygon with 5 sides. Each interior angle in a regular pentagon has a measure of 108 °.

Perimeter: The distance around a figure.

Permutation: The action of changing the arrangement, especially the linear order, of a set of items.

Perpendicular lines: Two lines, segments or rays that intersect to form right angles.

Pictograph: A graph that uses pictures to show and compare information.

Plane: A flat surface that extends infinitely in all directions.

Point: An exact location or position. It has no size, only position.

Polygon: A closed plane shape made with three or more straight sides.

Prime number: A whole number that has exactly two factors, 1 and itself.

Probability: The chance an event will occur.

Product: The answer to a multiplication problem. EXAMPLE: 6 x 2 = 12; the product is 12.

Properties of Operations: An operation works to change numbers. There are six operations: addition, subtraction, multiplication, division, raising to powers, and taking roots.

Protractor: An instrument used in measuring or drawing angles.


Pyramid: A solid figure with a polygon base and triangular sides that meet at a single point (vertex).

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Quadrants: The four regions of a coordinate plane that are separated by the axes.

Quadrilateral: A polygon with 4 sides.

Quotient: The answer that is a result of dividing one number by another.

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Radius: A line segment that has one endpoint on a circle and the other endpoint at the center of the circle.

Range: The difference between the greatest and least numbers in a set of data.

Rate: A ratio that compares two quantities having different units (EXAMPLE: 95 miles in 2 hours).

Ratio: A comparison of two numbers using division.

Ray: A part of a line that has one endpoint and continues without end in one direction.

Rectangular prism: A solid figure in which all six faces are rectangles.

Reflection (flip): A transformation that produces the mirror image of a figure.

Reflex Angles:  An angle greater than 180°.

Regular polygon: A polygon that has all sides congruent and all angles congruent.

Remainder: The amount left over when a number cannot be divided equally.

Repeating decimal: A decimal that has a repeating sequence of numbers after the decimal point.

Rhombus: A parallelogram with four equal sides.

Right angle: An angle that measures exactly 90º.

Right triangle: A triangle that has a 90º angle.

Rotation (turn): A movement of a figure that turns that figure around a fixed point.

Round:  Changing a number to its nearest group of ten, hundred, thousand, etc.  (e.g. 631 rounded to the nearest ten = 630; 631 rounded to its nearest hundred = 600; 631 rounded to its nearest thousand = 1,000)

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Scalene triangle: A triangle in which no sides are equal.

Similar polygons: Polygons that have the same shape, but not necessarily the same size. Corresponding sides of similar polygons are proportional.

Sphere: A solid figure that has all points the same distance from the center.

Square: (noun) A 4-sided polygon where all sides have equal length and every angle is a right angle (90°).


Square: (verb) To rasie a number or quantity to the second power. (The number is multiplied by itself.) (x)(x)

Stem and leaf plot: A way to show a list of numbers in a graph format, where each data value is split into a STEM and a LEAF (usually the digit in the ones place). Example: the numbers 22, 24 and 28 have a stem of "2" and "2", "4", "8" are the leafs.


Straight angle: An angle with a measure of 180º.

Sum: The answer to an addition problem. EXAMPLE: 12 + 7 = 19; the sum is 19.

Supplementary Angles:  Two angles whose measurements add to 180°.

Symmetry: When a figure can be divided by one straight line resulting in two halves that are mirror images.


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Tally chart: A table that uses tally marks to record data.

Terminating decimal: A decimal that contains a finite number of digits.

Tessellate: To combine plane figures so that they cover an area without any gaps or overlaps.

Transformation: The moving of a figure by a translation (slide), rotation (turn) or reflection (flip).

Translation (slide): A movement of a figure to a new position without turning or flipping it.

Trapezoid: A quadrilateral with exactly one pair of parallel sides.

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Unit price: The price of a single item or amount (EXAMPLE: $3.50 per pound).

Unit rate: A rate with the second term being one unit (EXAMPLE: 50 mi/gal, 4.5 km/sec).

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Variable: A letter or symbol that stands for a number or numbers.

Venn diagram: A diagram that shows relationships among sets of objects.

Vertex: A point where lines, rays, sides of a polygon or edges of a polyhedron meet (corner).

Vertical Angles: Angles opposite each other when two lines cross.

Volume (capacity): The amount of space (in cubic units) that a solid figure can hold.

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Whole number: Any of the numbers 0, 1, 2, 3, 4, 5, … (and so on).

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X-axis: The horizontal number line on a coordinate plane.

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Y-axis: The vertical number line on a coordinate plane.

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