Retroactive
Part of speech: adjective
Definition: Extending in scope, effect, application or influence to a prior time or to prior conditions
Retrospective
Part of speech: noun
Definition: an exhibition of works from an extended period of an artist's activity
Part of speech: adjective
Definition: of, relating to, or contemplating the pastlooking backwardsaffecting or influencing past things; retroactive
Example sentence: It is a simple but sometimes forgotten truth that the greatest enemy to present joy and high hopes is the cultivation of retrospective bitterness.