in effect inef·fect common adverb (1) adjective (1) adverb 1. in actuality or reality or fact “she is effectively his wife” “in effect, they had no choice” Synonymseffectivelyin effect adjective 1. exerting force or influence “the law is effective immediately” “a warranty good for two years” “the law is already in effect (or in force)” Synonymseffectivegoodin effectin force Similaroperative Related words Word family in effect Pertaining to effective WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.