a relative by marriage
- (postpositive; in combination)
related by marriage: a sister-in-law
WordReference Random House Learner's Dictionary of American English © 2026
ˈin-ˌlaw,
n. [countable]
WordReference Random House Unabridged Dictionary of American English © 2026- a relative by marriage:In-laws may present problems in a marriage.
- As the example above shows, the word in-law has as its plural form in-laws. But when a compound noun is formed with -in-law, such as brother-in-law, sister-in-law, mother-in-law, etc., its plural is formed by making the first part of the compound plural, and leaving -in-law unchanged:brothers-in-law, sisters-in-law, mothers-in-law.
in-law
(in′lô′),USA pronunciation n.
in•law (in lô′, in′lô′),USA pronunciation v.t. [Law.]
in′law′ry, n.
- a relative by marriage.
- back formation from mother-in-law, brother-in-law, etc. 1890–95
in•law (in lô′, in′lô′),USA pronunciation v.t. [Law.]
- Lawto restore (an outlaw) to the benefits and protection of the law.
- Middle English inlawen, Old English inlagian. See in-1, law bef. 1000
Collins Concise English Dictionary © HarperCollins Publishers::
'inlaw' also found in these entries (note: many are not synonyms or translations):