ex post facto

Use the adjective ex post facto to describe something that influences events in the past, like an ex post facto pay raise, which reimburses you for work you've done already.

Ex post facto is a Latin phrase that essentially means "retroactive," or affecting something that's already happened. You're most likely to come across ex post facto in a legal context, since lawyers talk about ex post facto law, which can change the punishment for a crime that occurred before a law went into effect, for example. In Latin, it means "from what is done afterwards."

Definitions of ex post facto

adj affecting things past

retro, retroactive
concerned with or related to the past

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