1. Parallelogram
Definition A quadrilateral with two pairs of parallel sides

2. Trapezoid
Definition A quadrilateral with exactly one pair of parallel sides.

3. Rectangle
Definition A parallelogram with four right angles. An equiangular quadrilateral

4. Rhombus
Definition A quadrilateral with four congruent sides. An equilateral quadrilateral

5. Square
Definition A quadrilateral with four congruent sides and four right angles. A regular quadrilateral.

6. Kite
Definition A quadrilateral with two pairs of consecutive sides congruent and no opposite sides congruent.

7. Median of a Triangle
A segment that has its endpoints on a vertex of the triangle and the midpoint of the opposite side

8. Altitude of a Triangle
The perpendicular segment from a vertex of the triangle to the line containing the opposite side.
Note: An altitude can be inside or outside the triangle. It can also be one of the sides of the triangle.

9. Angle Bisector in a Triangle
a segment from a vertex to the opposite side that separates the angle into two congruent angles