| a triangle with all angles less than 90o | Acute Triangle |
| two shapes of exactly the same size and proportions | Congruent |
| line segment that connects two nonadjacent vertices of a polygon | Diagonal |
| a triangle with all sides the same measure | Equilateral Triangle |
| a six sided polygon | Hexagon |
| a triangle with 2 sides the same measure | Isosceles Triangle |
| a triangle with one angle that is greater than 90o | Obtuse Triangle |
| an 8 sided polygon | Octagon |
| a quadrilateral with 2 pairs of parallel sides | Parallelogram |
| a five sided polygon | Pentagon |
| a closed plane figure made by three or more line segments | Polygon |
| a four sided polygon | Quadrilateral |
| a parallelogram with four 90o angles | Rectangle |
| a polygon in which all sides and angles are congruent | Regular Polygon |
| a parallelogram with 4 equal sides | Rhombus |
| a triangle with one angle that is 90o | Right Triangle |
| a triangle with no side having an equal measure | Scalene Triangle |
| a rectangle with 4 equal sides | Square |
| a quadrilateral with only 1 pair of parallel sides | Trapezoid |
| common endpoints that form a "corners" of a polygon | Vertices |