Definition of ex post facto in US English:

ex post facto

adverb & adjective

  • With retroactive effect or force.

    as adjective ‘ex post facto laws’
    backdated, retroactive, ex post facto, backward-looking
    View synonyms


Erroneous division of Latin ex postfacto ‘in the light of subsequent events’.


ex post facto

/ˌeks pōst ˈfaktō//ˌɛks poʊst ˈfæktoʊ/