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Synonyms

sister-in-law

American  
[sis-ter-in-law] / ˈsɪs tər ɪnˌlɔ /

noun

  • sisters-in-law
    plural
  1. the sister of one's spouse.

  2. the wife of one's brother or sister.

  3. the wife of one's spouse's sister or brother.


sister-in-law British  

noun

  1. the sister of one's husband or wife

  2. the wife of one's brother

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

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.

See Examples For:

I’ve become really close with my sister-in-law, and almost every Sunday, we meet for what we call “tea time.”

From Los Angeles Times Aug. 7, 2026

Has your sister-in-law, for better or for worse, saved you an awful lot of time and work that goes into being an executor?

From MarketWatch Aug. 7, 2026

He said his niece was a "very, very good person" and his sister-in-law was "a very helpful person".

From BBC Jul. 24, 2026

When they caught wind of the mysterious suitor, Danielle’s mom, sister and sister-in-law each found his LinkedIn page.

From The Wall Street Journal Jul. 1, 2026

Wondering if the acquaintance had gotten the name of the hotel wrong, Frear left his sister-in-law and Wood at the St. James and ran three blocks to another large hotel, the Sherman House.

From "The Great Fire" by Jim Murphy

She exchanged postcards with former sisters-in-law and her first husband’s second wife.

From Salon Feb. 9, 2025

"My father, my brother, my sisters-in-law and my friends are gone," says Delfino.

From BBC Feb. 7, 2025

His mother was ill, so one of her sisters-in-law filled out the registration card and submitted it to the city to produce a birth certificate, Didier Optowsky said.

From Los Angeles Times Apr. 26, 2024

Moreno's wife, one of their daughters, two of his brothers and two sisters-in-law are also among those allegedly connected to the case, Salazar said.

From Reuters Feb. 22, 2023

Patti starts pointing out faces and naming my father's cousins and their sisters and sisters-in-law and brothers and brothers-in-law.

From "Born Behind Bars" by Padma Venkatraman

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