/ Thesaurus / E Synonyms of ex post facto Find synonyms for: Adjective1. ex post facto, retroactive, retro, retrospective (vs. prospective)usage: affecting things past; "retroactive tax increase"; "an ex-post-facto law"; "retro pay"WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: dispel Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language