father-in-law

[ fah-ther-in-law ]

noun

, plural fa·thers-in-law.

1. the father of one's spouse.

father-in-law

noun

1. the father of one's wife or husband

Word History and Origins

Origin of father-in-law¹

First recorded in 1350–1400; Middle English fader in lawe; father, 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

Related Words

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