retroactive

UK: ˌretrəʊˈæktɪv | US: ˌretroʊˈæktɪv

Definition

  1. adj. taking effect from a date in the past

  2. adj. influencing or applying to past events

Structure
retro <backward>act <do>ive <adjective suffix>
Etymology

The word "retroactive" combines Latin-derived morphemes:

  1. "Retro" (from Latin retro, meaning "backward") indicates direction or time reversal.
  2. "Act" (from Latin agere, "to do") refers to action or effect.
  3. The suffix "-ive" (from Latin -ivus) forms adjectives denoting tendency or capacity.
    The term emerged in the early 17th century, originally legal jargon to describe laws applying to prior actions. Its logic mirrors "acting backward in time."
Examples

  1. The new tax policy is retroactive to January.

  2. Retroactive pay increases benefited employees for past work.

  3. Judges rarely approve retroactive changes to contracts.

  4. The software update included retroactive bug fixes.

  5. Critics argued the rule was unfairly retroactive.