| Chord | A line segment whose endpoints are on a circle. |
| Circumference | The distance around a circle. |
| Composite number | A whole number having more than two factors. |
| Diameter | A line segment that has endpoints on a circle and passes through the center of the circle. |
| Expanded notation | A way to write numbers that shows the value of each digit |
| Greatest common factor (GCF) | The largest factor that 2 or more numbers have in common. |
| Heptagon | A polygon with 7 sides. |
| 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). |
| 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 plot | A graph showing the frequency of data on a number line. |
| Nonagon | A polygon with 9 sides. |
| Plane | A flat surface that extends infinitely in all directions. |
| Prime number | A whole number that has exactly two factors, 1 and itself. |
| Quadrants | The four regions of a coordinate plane that are separated by the axes. |
| 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 (e.g., 95 miles in 2 hours). |
| Ratio | A comparison of two numbers using division. |
| Regular polygon | A polygon that has all sides congruent and all angles congruent. |
| Repeating decimal | A decimal that has a repeating sequence of numbers after the decimal point. |
| Similar polygons | Polygons that have the same shape, but not necessarily the same size. Corresponding sides of similar polygons are proportional. |
| Straight angle | An angle with a measure of 180º. |
| Terminating decimal | A decimal that contains a finite number of digits. |
| Transformation | The moving of a figure by a translation (slide), rotation (turn) or reflection (flip). |
| Unit price | The price of a single item or amount (e.g., $3.50 per pound). |
| Unit rate | A rate with the second term being one unit (e.g., 50 mi/gal, 4.5 km/sec). |
| Venn diagram | A diagram that shows relationships among sets of objects. |
| Whole number | Any of the numbers 0, 1, 2, 3, 4, 5, … (and so on). |
| X-axis | The horizontal number line on a coordinate plane. |
| Y-axis | The vertical number line on a coordinate plane. |