RETROACTIVE
retroactive
(adjective) descriptive of any event or stimulus or process that has an effect on the effects of events or stimuli or process that occurred previously
Source: WordNet® 3.1
Etymology
Adjective
retroactive (not comparable)
Extending in scope, effect, application or influence to a prior time or to prior conditions
Source: Wiktionary
Re`tro*act"ive, a. Etym: [Cf. F. rétroactif.]
Definition: Fitted or designed to retroact; operating by returned action;
affecting what is past; retrospective. Beddoes. Retroactive law or
statute (Law), one which operates to make criminal or punishable, or
in any way expressly to affect, acts done prior to the passing of the
law.
Source: Webster’s Unabridged Dictionary 1913 Edition