Phrase guide

ab initio

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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  • US: /ˌæb ɪˈnɪʃ.i.oʊ/
  • US: /ˌæb əˈnɪt.i.oʊ/
  • US: /ˌɑb əˈnɪt.i.oʊ/

1

adv

Meaning 1

From the time when a law, legal right or decree, contract, ownership interest, partnership (etc.) comes into force.

Definition source: English Wiktionary via Wiktextract

Topics: law

Examples

  • As the Act was passed without the required quorum, the constitutional court struck down the Act and declared it to be void ab initio

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

adv

Meaning 2

Calculated from first principles, i.e. from basic laws without any further additional assumptions.

Definition source: English Wiktionary via Wiktextract

Topics: sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

3

adv

Meaning 3

Taken with no prior qualifications.

Definition source: English Wiktionary via Wiktextract

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

4

adverb

Meaning 4

at the beginning

Definition source: Princeton WordNet 3.0

Examples

  • at first he didn't notice anything strange

Meaning relationships

Synonyms: initially

Antonyms: none provided

History

Etymology

From Latin ab (“from”) + initiō, ablative singular of initium (“beginning”).

Across languages

Translations

10 source translations are retained for this English entry.

  • Dutch: ab initio — referring to the time from when a legal document comes into force
  • Dutch: vanaf het begin — referring to the time from when a legal document comes into force
  • Hindi: आदितः (āditaḥ) — referring to the time from when a legal document comes into force
  • Polish: ab initio — referring to the time from when a legal document comes into force
  • Russian: с возникнове́ния (s vozniknovénija) — referring to the time from when a legal document comes into force
  • Russian: от нача́ла (ot načála) — referring to the time from when a legal document comes into force
  • Spanish: ab initio — referring to the time from when a legal document comes into force
  • Spanish: desde el principio — referring to the time from when a legal document comes into force
  • Polish: ab initio — calculated from first principles, i.e. from basic laws without any further additional assumptions
  • Polish: ab initio — taken with no prior qualifications