retrogressive adj.

late 14c., of planets, "appearing to move in the sky contrary to the usual direction," from Latin retrogradus "going back, moving backward," from retrogradi "move backward," from retro "backward, reverse" (see retro-) + gradi "to go, step" (from PIE root *ghredh- "to walk, go"). General sense of "tending to revert" is recorded from 1530s; that of "directed backward, in a direction contrary to the original motion" is from 1620s. .

word-forming element making adjectives from verbs, meaning "pertaining to, tending to; doing, serving to do," in some cases from Old French -if, but usually directly from Latin adjectival suffix -ivus (source also of Italian and Spanish -ivo). In some words borrowed from French at an early date it has been reduced to -y (as in hasty, tardy).