sister-in-law

[ sis-ter-in-law ]

noun

, plural sis·ters-in-law.

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

noun

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

Word History and Origins

Origin of sister-in-law¹

First recorded in 1400–50; late Middle English syster in lawe; 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

“I have a sister-in-law who I will not talk to, because if I call her we end up shouting and I just hang up on her.”

From BBC

The videos came to light after Hwang's sister-in-law shared them on social media last June, in an attempt to blackmail him.

From BBC

A much loved daughter, sister, sister-in-law and aunt, Caoimhe Morgan was remembered as always smiling, happy and outgoing.

From BBC

A few weeks ago, I had dinner with my mother's sister-in-law and her daughter.

From Salon

Nephew John F. Kennedy Jr. died, with his wife and sister-in-law, when the plane he was flying crashed in 1999 in the Atlantic Ocean.

From Los Angeles Times

Related Words

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