Basic Geometry Terms

Front

Point

Back

A location that has no size and is represented by a dot

Front

Line

Back

A straight path that has no thickness and extends forever.

Front

Plane

Back

A flat surface that has no thickness and extends forever.

Front

Collinear

Back

Points that lie on the same line (e.g., points K, M, N on the same line).

Front

Coplanar

Back

Points that lie in the same plane.

Front

Segment

Back

A part of a line with two endpoints (e.g., segment XY or YX).

Front

Endpoint

Back

A point at one end of a segment or the starting point of a ray.

Front

Ray

Back

A part of a line that starts at an endpoint and extends forever in one direction (e.g., ray XY).

Front

Opposite Rays

Back

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

Front

Postulates

Back

A statement that is accepted as true without proof.