noun, plural moth·ers-in-law.

the mother of one's husband or wife.

Origin of mother-in-law

1350–1400; Middle English modyr in lawe Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for mother-in-law

Contemporary Examples of mother-in-law

Historical Examples of mother-in-law

  • His mother-in-law had always lived with him, and she was "difficult."

    Tiverton Tales

    Alice Brown

  • That woman, I am quite sure and confident, will be our mother-in-law.'

    Little Dorrit

    Charles Dickens

  • In other homes the daughter-in-law serves her mother-in-law.

  • I am but mother-in-law to them,' she said, 'having not been married yet full two years.


    James Anthony Froude

  • But God blessed Ruth much more than Orpah, because she loved her mother-in-law.

    Things as They Are

    Amy Wilson-Carmichael

British Dictionary definitions for mother-in-law


noun plural mothers-in-law

the mother of one's wife or husband
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

Word Origin and History for mother-in-law

mid-15c., "mother of one's spouse," from mother (n.1) + in-law. Also in early use, "stepmother." In British slang c.1884, mother-in-law was "a mixture of ales old and bitter."

Online Etymology Dictionary, © 2010 Douglas Harper