Phrase guide

ex post facto

adj · adv · 4 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

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No pronunciation record was provided for this word.

1

adj

Meaning 1

Retroactive.

Definition source: English Wiktionary via Wiktextract

Usage: not-comparable

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

adj

Meaning 2

Retroactive.

Formulated or enacted after some event, and then retroactively applied to it.

Definition source: English Wiktionary via Wiktextract

Usage: not-comparable

Topics: law

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

3

adv

Meaning 3

By retroactive application of a law formulated or enacted after the deed in question.

Definition source: English Wiktionary via Wiktextract

Usage: not-comparable

Topics: law

Examples

  • What he did was not a crime when he did it, but he was convicted ex post facto.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

4

adjective satellite

Meaning 4

affecting things past

Definition source: Princeton WordNet 3.0

Examples

  • retroactive tax increase
  • an ex-post-facto law
  • retro pay

Meaning relationships

Synonyms: retroactive, retro

Antonyms: none provided

History

Etymology

From Latin ex (“from”) + post (“after”) + factō, ablative of factum (“deed”). In Latin, ex takes the ablative case, while post takes the accusative case. (See Wikipedia for a discussion of the grammatical form and usage of this phrase.)

Across languages

Translations

4 source translations are retained for this English entry.

  • Hungarian: visszamenőleges — retroactive
  • Polish: ex post facto — retroactive
  • Finnish: taannehtiva — formulated or enacted after some event, then retroactively applied to it
  • Polish: ex post facto — formulated or enacted after some event, then retroactively applied to it