brother-in-law
Americannoun
plural
brothers-in-law-
the brother of one's spouse.
-
the husband of one's sister or brother.
-
the husband of one's spouse's sister or brother.
noun
-
the brother of one's wife or husband
-
the husband of one's sister
-
the husband of the sister of one's husband or wife
Etymology
Origin of brother-in-law
First recorded in 1350–1400; Middle English brother in law(e); see origin at brother, 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.
While we were talking, her brother-in-law, Jeremy, came outside.
From Salon • Apr. 19, 2026
Ahmad said that those were photos from a trip to see his brother-in-law, who was training at a U.S. military base.
From Slate • Apr. 19, 2026
The cause of death, the brother-in-law was told, was cardiac arrest.
From The Wall Street Journal • Apr. 5, 2026
Around 1 a.m., seven hours after Ashaal failed to return home, a cousin and brother-in-law contacted friends, hospitals and the various security headquarters in Aden.
From Los Angeles Times • Mar. 30, 2026
Apart from being the brother-in-law and legal partner of Harold Wolpe, who performed a number of transactions for us through his office, he had no involvement whatsoever with the ANC or MK.
From "Long Walk to Freedom" by Nelson Mandela
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.
