brother-in-law
Pluralbrothers-in-law
- 1The brother of one's spouse.
Diane's brother-in-law, her husband's older brother, runs the family bakery.
He gets along well with all three of his brothers-in-law, his wife's brothers.
Note
Whichever relative it names, the word makes its plural the same way: the -s goes on brother, giving brothers-in-law. Brethren-in-law survives only as an archaic plural. Brother-in-laws is colloquial and nonstandard, so you may hear it, but it is best kept out of writing. The compound goes back to Middle English brother-in-lawe, built simply from brother plus -in-law.
- 2The husband of one's sibling.
Her brother-in-law joined the firm shortly after marrying her sister.
Both of his sisters married teachers, so his two brothers-in-law trade lesson plans at every holiday dinner.
- 3The husband of one's spouse's sibling, a male relative of one's own generation connected through two marriages.
At the reunion, my brother-in-law, my wife's sister's husband, organized the whole cookout.
The two men married sisters years ago and have been brothers-in-law ever since.
Note
Two marriages lie between these men, because each married one of a pair of siblings. Where precision matters, the relation has its own name, co-brother-in-law, which keeps it apart from a spouse's brother and a sibling's husband. Plain brother-in-law still serves. The Dictionary of Irish Biography (2009), writing of Tom Kettle, calls Francis Sheehy-Skeffington simply his brother-in-law.
Less common meaning
- 4The brother of one's sibling's spouse: a male relative of one's own generation, connected through a sibling's marriage.
Her brother-in-law (her sister's husband's brother) flew in from Denver for the holidays.
Ever since Priya married his brother, Daniel has golfed most Sundays with her two brothers, whom he now calls his brothers-in-law.
Note
Of all the uses, this one is uncommon. Here the tie reaches past a sibling's spouse to that spouse's own brother. It belongs with the co-brother-in-law relation, two degrees of marriage away. Many speakers keep brother-in-law for the closer ties, so it is often clearer to spell the link out, as in "my sister's husband's brother," than to rely on the bare word.
Use it in a sentence
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Origin
From Middle English brother-in-lawe, equivalent to 'brother' plus the suffix '-in-law'.