1520s, "to draw back," of persons, from obsolete French resiler "withdraw from an agreement," or directly from Latin resilire "to jump back" (see resilience). The meaning "spring back, start back, recoil" (of material things, especially elastic bodies) is from 1708. Related: Resiled; resiling.
"act of turning or bending backward," 1590s, from Medieval Latin retortionem (nominative retortio), noun of action from past-participle stem of Latin retorquere "turn back, twist back, throw back," from re- "back" (see re-) + torquere "to twist" (from PIE root *terkw- "to twist"). Also retorsion (1640s).
"bent backward," 1776, in botany, from Modern Latin retroflexus, past participle of retroflectere "to bend back," from retro "back" (see retro-) + flectere "to bend" (see flexible). The verb "to turn or fold back" (1898) is a back-formation from retroflexed (1806), which is from the adjective. Related: Retroflexion.
early 15c., retracten, "to draw (something) back, draw in, absorb," from Old French retracter (14c.) and directly from Latin retractus, past participle of retrahere "to draw back" (see retraction).
Sense of "to revoke, recant, take back" (an offer, declaration, etc.), is attested from 1540s, probably a back-formation from retraction. Of body parts, etc., "draw or shrink back, draw in," 1660s. Related: Retracted; retracting.
1640s (intransitive), of fluids, "to surge or rush back, be poured back," a back formation from regurgitation, or else from Medieval Latin regurgitatus, past participle of regurgitare. Transitive sense of "to vomit, cast out from the stomach" is attested by 1753. Related: Regurgitated; regurgitating.
in anatomy, "of or pertaining to the back," late 14c., from Old French dorsal (14c.) or directly from Medieval Latin dorsalis, corresponding to Latin dorsualis "of the back," from dorsum "back," which is of uncertain origin. Related: Dorsally.
