Definition of post facto in US English:

post facto

adjective

  • Occurring, made, or enacted after the event; done with hindsight.

adverb

  • = post factum.

Origin

Late 16th century; earliest use found in George Whetstone (d. 1587), writer. From classical Latin postfacto. With use as adjective compare later post-fact, post factum. With use as adverb compare slightly earlier post factum.

Pronunciation

post facto

/ˌpəʊs(t) ˈfaktəʊ/