Dictionary.com

brother-in-law

[ bruhth-er-in-law ]
/ ˈbrʌð ər ɪnˌlɔ /
Save This Word!

noun, plural broth·ers-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.
QUIZ
CAN YOU ANSWER THESE COMMON GRAMMAR DEBATES?
There are grammar debates that never die; and the ones highlighted in the questions in this quiz are sure to rile everyone up once again. Do you know how to answer the questions that cause some of the greatest grammar debates?
Question 1 of 7
Which sentence is correct?

Origin of brother-in-law

First recorded in 1350–1400; Middle English brother in law(e); see origin at brother, in, law1; 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
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use brother-in-law in a sentence

British Dictionary definitions for brother-in-law

brother-in-law

noun plural brothers-in-law
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
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
FEEDBACK