Main Entry: ret·ro·ac·tive

Pronunciation: \-ˈak-tiv\

Function: adjective

Etymology: French rétroactif, from Latin retroactus, past participle of retroagere to drive back, reverse, from retro- + agere to drive — more at agent

Date: 1611

: extending in scope or effect to a prior time or to conditions that existed or originated in the past; especially : made effective as of a date prior to enactment, promulgation, or imposition <retroactive tax>

— ret·ro·ac·tive·ly adverb

— ret·ro·ac·tiv·i·ty \-ˌak-ˈti-və-tē\ noun