[ fah-ther-in-law ]
/ ˈfɑ ðər ɪnˌlɔ /
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noun, plural fa·thers-in-law.

the father of one's spouse.



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Origin of father-in-law

First recorded in 1350–1400; Middle English fader in lawe; see origin at father, 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. 2021

British Dictionary definitions for father-in-law


noun plural fathers-in-law

the father 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
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