father-in-law
Americannoun
plural
fathers-in-lawnoun
Etymology
Origin of father-in-law
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
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
His father-in-law, billionaire businessman Ronald Lauder, is a long-time Trump donor and ally.
From BBC • Jan. 30, 2026
Warsh’s father-in-law, Ronald Lauder, is a former classmate of Trump’s and a major Republican donor.
From The Wall Street Journal • Jan. 30, 2026
Warsh’s father-in-law is Ron Lauder, a longtime friend of Trump’s.
From Barron's • Jan. 30, 2026
My late father-in-law wrote a book once called “Die Broke.”
From Los Angeles Times • Jan. 28, 2026
“As you can see, this is a better proposition than the chinchillas,” concluded his future father-in-law without noticing the young man’s nervous whimpering.
From "The House of the Spirits: A Novel" by Isabel Allende
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
