ab initio

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

adverb

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

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

First used Early 17ᵗʰ century.

Meanings

adverb

alternative ab init

  1. lawFrom the time when a law, legal right or decree, contract, ownership interest, partnership (etc.) comes into force.First known use Early 17ᵗʰ century.

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

    1 more example

    Any child marriage solemnised in contravention of an injunction order issued under section 13, whether interim or final, shall be void ab initio.

    2007, Parliament of India, “Section 14”, in Prohibition of Child Marriage Act, 2006, archived from the original on 15 Jul 2024, page 4
  2. sciencesCalculated from first principles, i.e. from basic laws without any further additional assumptions.

    […] this soul does not exist ab initio, as orthodox Christianity teaches; it has to be brought into existence by a process of guided self-observation. However, this is rarely achieved, owing to man's unique ability to be distracted from spiritual matters by everyday trivia.

    1983, Monty Python, The meaning of life, at about 1h 15'
  3. Taken with no prior qualifications.

Synonyms & antonyms

adverbat the beginning

Synonym sets from Open English WordNet, CC BY 4.0.

Origin

  1. Latinab initiō“from the beginning”
  2. Englishab initio

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

Full word history & related roots →

Translations

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

ab initio. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/ab%20initio

MLA

“ab initio.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/ab%20initio. Accessed November 3, 2026.

Chicago

WatkinsX Dictionary, s.v. “ab initio,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/ab%20initio.

Source: ab initio on Wiktionary, CC BY-SA 4.0.