Basic Geometry Terms and Definitions

Lines in the same plane that do not intersect.

• Bisector

• Collinear

• Coplanar

• Parallel Lines

Two rays that have a common endpoint and form a line.

• Opposite Rays

• Plane

• Parallel

• Midpoint

A line, ray or segment that divides a segment into two congruent segments.

• Ray

• Midpoint

• Bisector

• Plane

A portion of a line that starts at a point (the endpoint) and continues forever in one direction.

• Point

• Parallel

• Ray

• Line

Points or lines that are not in the same plane.

• Non-Coplanar

• Coplanar

• Collinear

• Parallel

Lines that are not coplanar and do not intersect.

• Collinear

• Skew Lines

• Non-Collinear

• Ray

Points or lines all in one plane.

• Ray

• Collinear

• Point

• Coplanar

The set of all points in three dimensions.

• Collinear

• Space

• Opposite Rays

• Parallel

Two segments that have the same length.

• Line Segment

• Parallel

• Coplanar

• Congruent Segments

Three or more points not all of which lie on the same line.

• Non-Collinear

• Collinear

• Non-Coplanar

• Ray