An Etymological Dictionary of Astronomy and Astrophysics

Moving backward; having a backward motion or direction. → retrograde motion.

Etymology (EN): M.E., from L. retrogradus “going backward,” from retrogradi “move backward,” from retro- “backward” + gradi “to go, step.”

Etymology (PE): Pasrow, pasraft, from pas- “back, behind,” → back, + row, raft present and past stems of raftan “to go, walk;” (Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- “to go; to attack”).