1. a line traced by a point traveling in a constant direction; a line of zero curvature;

- Example: "the shortest distance between two points is a straight line"

WordNet (r) 3.0 (2006):

straight line n 1: a line traced by a point traveling in a constant direction; a line of zero curvature; "the shortest distance between two points is a straight line" [ant: curve, curved shape]