mother-in-law

[muhth-er-in-law]

noun

plural

mothers-in-law 

1. the mother of one's spouse.

mother-in-law

noun

1. the mother of one's wife or husband

Word History and Origins

Origin of mother-in-law¹

First recorded in 1350–1400; Middle English moder in lawe; 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

Related Words

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