This document defines several key geometry terms: - A segment is defined as two points on a line connected by all points between them. The endpoints are the defining points of the segment. - A ray is one endpoint point on a line extending in one direction. Opposite rays extend from the same endpoint in opposite directions. - The length of a segment is the distance between its two endpoints. On a number line, length is the absolute value of the difference between the coordinates. - Other terms defined include postulates, congruent, congruent segments, midpoint of a segment, and segment bisector. Practice problems are provided to reinforce the new definitions.