mother-in-law

American  

[muhth-er-in-law] / ˈmʌð ər ɪnˌlɔ /

noun

plural

mothers-in-law

1. the mother of one's spouse.

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mother-in-law British  

noun

1. the mother of one's wife or husband

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Etymology

Origin of mother-in-law

First recorded in 1350–1400; Middle English moder in lawe; see origin at mother ¹ ( def. ), in ( def. ), law ¹ ( def. ); 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

But John Oxenham saw the pictures taken in the skies near his Oxfordshire home and said he knew exactly where the sausage roll had come from - his mother-in-law.

From BBC • Apr. 15, 2026

"My mother-in-law is dead, my brother-in-law's wife too, and their son," said a man who did not want to give his name, adding that they all lived in the same building.

From Barron's • Apr. 8, 2026

In 2019, my mother-in-law suffered a stroke and moved into our home while she recovered.

From Los Angeles Times • Apr. 3, 2026

“My father is 80, my mother and mother-in-law are in their mid-70s. All of us try to be everywhere at all times, and we are like a significant portion of the country doing unpaid care.”

From MarketWatch • Mar. 4, 2026

Even the scandalous news that her supposedly grieving mother-in-law seemed to be on the brink of remarriage did not force a peep from the precariously balanced Lady Constance.

From "The Unseen Guest" by Maryrose Wood

Related Words

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