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See also: sister in law



From Middle English suster-in-lawe; equivalent to sister +‎ in +‎ law.


sister-in-law (plural sisters-in-law)

  1. A female relative of one's generation, separated by one degree of marriage:
    1. The sister of one's spouse.
    2. The wife of one's sibling.
  2. (less common) Co-sister-in-law: The wife of one's sibling-in-law.
    1. The wife of the sibling of one's spouse.
    2. The sister of the spouse of one's sibling.

Usage notes[edit]

The plural sister-in-laws is occasionally seen, especially in American English, but this is considered incorrect by most sources; see, for example, [1].

Derived terms[edit]

Related terms[edit]


The translations below need to be checked and inserted above into the appropriate translation tables, removing any numbers. Numbers do not necessarily match those in definitions. See instructions at Wiktionary:Entry layout#Translations.