9 terms

line segment

part of a line with two endpoints

line

a line segment that has no end points

ray

a part of a line with one endpoint and one side goes on forever.

parallel lines

lines in the same plane that never intersect

perpendicular lines

two lines intersecting at or forming right angles

vertical angles

a pair of opposite congruent angles formed by intersecting lines

adjacent angles

are a pair of angles with a common vertex and a common side, but no common interior points

complementary angles

two angles whose sum is 90 degrees

supplementary angles

two angles whose sum is 180 degrees