EX POST FACTO Meaning of EX POST FACTO in English [ ˌɛks pəʊst'faktəʊ ]■ adjective & adverb with retrospective action or force.Originerroneous division of L. ex postfacto 'in the light of subsequent events'. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004