sister-in-law
Americannoun
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the sister of one's spouse.
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the wife of one's brother or sister.
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the wife of one's spouse's sister or brother.
noun
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the sister of one's husband or wife
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the wife of one's brother
Other Word Forms
Noun Inflected Forms
Etymology
Origin of sister-in-law
First recorded in 1400–50; late Middle English syster in lawe; see origin at sister, in, law 1; from Middle English in-lawe “in law,” i.e., “a person within the regulation and protection of the law,” based on the prohibition by Roman civil law and, later, Christian canon law, of marriages within four degrees of consanguinity, i.e., up to and including first cousins
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
A day later, a fire was discovered at the entrance to Sir Keir's Kentish Town home, which he still owned and was being rented out to his sister-in-law, Judith Alexander.
From BBC • Jun. 19, 2026
Crossover expert Paulo Szot was stylish as Signor Naccarelli, Fabrizio’s father, and Kelly Guerra had a fine Sondheim-esque number as Franca, Fabrizio’s embittered sister-in-law.
From The Wall Street Journal • Jun. 15, 2026
Her sister-in-law, Millicent Sedra, also spoke and scolded women who expect husbands to share housework.
From Salon • Jun. 12, 2026
Standing “square in the doorway like a nightclub bouncer,” Lindsay’s sister-in-law says, “I’m sorry we haven’t got space for you to stay here long term.”
From The Wall Street Journal • May 15, 2026
She was as uninterested in it as she was in her trousseau, and she left all decisions in the hands of her fiance and her future sister-in-law.
From "The House of the Spirits: A Novel" by Isabel Allende
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
