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co-brother-in-law (plural co-brothers-in-law)

  1. (uncommon) One's wife's sister's husband; or more generally one's spouse's brother-in-law, the brother of one spouse in relation to the siblings of the other spouse.
    1. (uncommon, in the plural) Men who marry sisters.
    • 2008, Daniel Bornstein & David Peterson, editor, Florence and Beyond: Culture, Society and Politics in Renaissance Italy, page 350:
      Knowing that he would be susceptible to the arguments of his persuasive co-brother-in-law Antonio de' Medici, Saminiato tried to avoid his company.
  2. (uncommon) One's brother-in-law or sister-in-law's brother; that is, one's sibling's spouse's brother (one's sister's husband's brother or one's brother's wife's brother).
    1. (in the plural) Men whose brother and sister are married to each other.

Usage notesEdit

  • The term is generally used in translation in South India (Karnataka, Tamil Nadu, Andhra Pradesh) where the local language makes the distinction. In common speech in traditionally English-speaking countries, brother-in-law may be used.
  • The primary usage is for one's wife's sister's husband.


  • co-brother (Karnataka, Tamil Nadu) (much more common)
  • (secondary sense): co-uncle (in relation to a common niece or nephew)

Coordinate termsEdit

Related termsEdit


Languages that have words for this relationship that are distinct from the word for brother-in-law. Not all are attested to have the second meaning above, though this may sometimes be an oversight.