Definition of retroactive adjective from the Oxford Advanced American Dictionary

 

retroactive

 adjective
adjective
NAmE//ˌrɛtroʊˈæktɪv//
 
(also retrospective)(of a new law or decision)
 
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intended to take effect from a particular date in the past rather than from the present date retroactive legislation retroactive pay increases
retroactively
 
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adverb The ruling will be applied retroactively.
See the Oxford Advanced Learner's Dictionary entry: retroactive