sister-in-law
Americannoun
plural
sisters-in-law-
the sister of one's spouse.
-
the wife of one's brother or sister.
-
the wife of one's spouse's sister or brother.
noun
-
the sister of one's husband or wife
-
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.
Natalie's sister in law, Holly McNally, told the court she remembered McCullagh being in the McNally family home, only to return 20 minutes later to say that he had forgotten his telephone.
From BBC • Mar. 13, 2026
The New York Times reported Thursday, based on a text message from Crosby’s sister in law, that the musician died Wednesday night.
From Seattle Times • Jan. 19, 2023
The elder Taylor on Tuesday said a cousin of Ghosn, who is his wife’s sister in law, helped persuade him to take the job.
From Reuters • Jun. 29, 2021
“That’s his smile,” said Jeanmarie Larsen, Cuffe’s sister in law.
From Washington Times • Nov. 29, 2019
Before he set out he paid a visit in form to his sister in law, and was much pleased with his reception.
From The History of England, from the Accession of James II — Volume 4 by Macaulay, Thomas Babington Macaulay, Baron
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.
