brother-in-law

[bruhth-er-in-law]

noun

plural

brothers-in-law 

1. the brother of one's spouse.

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

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

brother-in-law

noun

1. the brother of one's wife or husband

2. the husband of one's sister

3. the husband of the sister of one's husband or wife

Word History and Origins

Origin of brother-in-law¹

First recorded in 1350–1400; Middle English brother in law(e); 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

Do I tell my sister and brother-in-law that the turkey was undercooked last year and could have given us all food poisoning?

Read more on MarketWatch

Lee's brother-in-law said the children's other grandmother was sick with cancer and still did not know about the murders.

Read more on Barron's

Her husband and her brother-in-law beat Till, shot him in the head, and threw him into the Tallahatchie River.

Read more on Literature

Under the direction of the king’s brother-in-law Charles Brandon, extremely strong cables were attached to the Mary Rose and then fastened to two large surface ships sailing on either side of the sunken vessel.

Read more on Literature

The president’s brother-in-law, who was at the center of the scandal, denied involvement.

Read more on The Wall Street Journal

Related Words

• aunt 
• cousin 
• father 
• folk 
• mother 
• niece 
• sibling 
• uncle