Based on Latin illegitimus; equivalent to in- + legitimate.

• • IPA: /ɪlɪˈd͡ʒɪtɪmət/
  • (America) IPA: [ɪlɨˈd͡ʒɪɾəmɨt]
  • (New Zealand) IPA: /ɘlɘˈdʒɘtɘmɘt/
  • IPA: /ɪlɪˈd͡ʒɪtɪmeɪt/
  • (America) IPA: [ɪlɨˈd͡ʒɪɾəmeɪt]
  • (New Zealand) IPA: /ɘlɘˈdʒɘtɘmeɪt/

illegitimate

1. Not conforming to known principles, or established or accepted rules or standards.

   Synonyms: invalid

   Antonyms: valid

   • 1791 (date written), Mary Wollstonecraft, “The Prevailing Opinion of a Sexual Character Discussed”, in A Vindication of the Rights of Woman: With Strictures on Political and Moral Subjects, London: […] J[oseph] Johnson, […], published 1792, →OCLC ↗, page 38 ↗:

     […] it may be impossible to convince them that the illegitimate power which they obtain, by degrading themselves, is a curse […]

2. Not in accordance with the law.

   Synonyms: illegal, illicit, unlawful

   Antonyms: legal

3. Not sanctioned by marriage.
   • 1916, chapter 6, in Abraham Brill, transl., Leonardo da Vinci: A Psychosexual Study of an Infantile Reminiscence‎, New York: Moffat, Yard, page 118:

     His illegitimate birth deprived him of the influence of a father until perhaps his fifth year […]

   1. Born to unmarried parents.

      Synonyms: natural, Thesaurus:illegitimate

      an illegitimate child

      • c. 1602, William Shakespeare, “The Tragedie of Troylus and Cressida”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC ↗, [Act V, scene vii]:

        I am a bastard begot, bastard instructed, bastard in mind, bastard in valour, in every thing illegitimate.

      • 1838, Boz [pseudonym; Charles Dickens], chapter 51, in Oliver Twist; or, The Parish Boy's Progress. […], volume (please specify |volume=I, II, or III), London: Richard Bentley, […], →OCLC ↗:

        ‘This child,’ said Mr. Brownlow, drawing Oliver to him, and laying his hand upon his head, ‘is your half-brother; the illegitimate son of your father […] ’

   2. (dated) Having a child or children with a person to whom one is not married.
      • 1876, George Eliot [pseudonym; Mary Ann Evans], chapter 27, in Daniel Deronda, volume (please specify |volume=I to IV), Edinburgh, London: William Blackwood and Sons, →OCLC ↗:

        She had only to collect her memories, which proved to her that “anybody” regarded the illegitimate children as more rightfully to be looked shy on and deprived of social advantages than illegitimate fathers.

4. Not correctly deduced.

   Synonyms: illogical, invalid

   Antonyms: logical, valid

   an illegitimate inference

   • 1734, George Berkeley, The Analyst‎, London: J. Tonson, Section 27, pp. 44-45:

     […] it is illegitimate to reduce an Equation, by subducting from one Side a Quantity when it is not to be destroyed, or when an equal Quantity is not subducted from the other Side of the Equation:

5. Not authorized by good usage; not genuine.

   Synonyms: spurious

   an illegitimate word

6. (botany) Involving the fertilization of pistils by stamens not of their own length, in heterogonously dimorphic and trimorphic flowers.

   illegitimate union; illegitimate fertilization

   • 1877, Charles Darwin, chapter 1, in The Different Forms of Flowers on Plants of the Same Species‎:

     […] the legitimate unions between the two forms of the above nine species of Primula are much more fertile than the illegitimate unions; although in the latter case pollen was always taken from a distinct plant of the same form.

• See also Thesaurus:illegitimate

• legitimate

• illegit
• illegitimacy
• illegitimate theatre
• illegitimate theater

• illegitimately
• illegitimateness
• illegitimation
• illegitimize

• Russian: нелигитимный

• French: illégitime
• German: illegitim, unrechtmäßig
• Italian: illegale
• Portuguese: ilegal
• Russian: незако́нный

• Italian: illegittimo
• Portuguese: ilegítimo
• Russian: незаконный
• Spanish: ilegítimo, natural

• French: illégitime
• Italian: illegittimo
• Portuguese: ilegítimo

illegitimate (plural illegitimates)

1. A person born to unmarried parents.

   Synonyms: natural child, lovechild, bastard

   • 1966, Jean Rhys, Wide Sargasso Sea‎, New York: Norton, Part 2, p. 96:

     Her father and mine was a shameless man and of all his illegitimates I am the most unfortunate and poverty stricken.

• Spanish: hijo ilegítimo

illegitimate (illegitimates, present participle illegitimating; simple past and past participle illegitimated)

1. (transitive) To make illegitimate.