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
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.
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
Accepting the award, Giuffre's sister-in-law Amanda Roberts said the book was "a true testament to what a survivor's voice can do when finally given the space to be heard".
From BBC • May 11, 2026
News, which cited emails between Joseph and his sister-in-law Anna Duggar that were exchanged March 21 after Anna and Kendra had spoken.
From Los Angeles Times • Apr. 6, 2026
I didn’t fully become One with a ring until this January when my extremely fit, pickleball-playing sister-in-law bowed out one morning from a family hike at the urging of her ring.
From The Wall Street Journal • Mar. 29, 2026
I’d get Nora as my sister-in-law, plus an awesome older sister in college.
From "Leah on the Offbeat" by Becky Albertalli
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.
