1. (n.) A straight line (or the length of such line) connecting any point, as of a curve, with a fixed point, or pole, round which the straight line turns, and to which it serves to refer the successive points of a curve, in a system of polar coordinates. See Coordinate.
2. (n.) An ideal straight line joining the center of an attracting body with that of a body describing an orbit around it, as a line joining the sun and a planet or comet, or a planet and its satellite.
Thesaurus Entries
aeronautics, air lane, air route, air service, airway, astronautics, aviation, axis, ballooning, beeline, blind flying, chord, cloud-seeding, commercial aviation, contact flying, corridor, cruising, cut, cutoff, diagonal, diameter, direct line, directrix, edge, flight, flying, general aviation, gliding, great-circle course, lane, normal, path, perpendicular, pilotage, radius, radius vector, right line, sailing, sailplaning, secant, segment, shortcut, shortest way, side, soaring, straight, straight course, straight line, straight stretch, straightaway, streamline, tangent, transversal, vector, winging
