Is there a name for the relationship of my wife’s sister’s husband in English? Or in case of a lady, what is the relationship of her husband’s brother’s wife called? There are words for these relationships in Indian languages like Tamil.

I have heard instances of the words “co-brother” and “co-sister” being used in India. But, I strongly suspect that these usages are Indian.


I suspect they are, too - you'll be having co-son and co-son's mate next!

Seriously, you are talking about in-laws here.

From Wikipedia:

A brother-in-law (plural brothers-in-law) is the brother of one's spouse, the husband of one's sibling, the husband of one's spouse's sibling [relevant in the first case you mention], or the brother of one's sibling's spouse.

You can work out what sister-in-law covers.

Oh, and the perhaps unfamiliar terms used by Wikipedia:

sibling - a brother or sister

spouse - a husband or wife

... that is, they are hypernyms (like cutlery for knives, forks, ...)

  • 5
    Ah! Disappointing. :-) I was expecting a new word to come up. I suppose English is less specific about relationships when compared to Indian languages. Tamil, an Indian language, has different words for the relationships of father's brother and mother's brother. English uses the word "uncle" for both. The same generalization applies in this case well. – MediumOne Sep 26 '12 at 8:15
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    In English, the terms maternal and paternal are sometimes added to indicate from which side of the family the relationship derives. This is more common with grandparents, as in my maternal grandfather (my mother's father). Also, with aunts and uncles, there is generally no linguistic distinction as to whether the relationship is based on blood or marriage. – bib Sep 26 '12 at 13:12
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    "To the poet, the distinction between 'father' and "grandfather" is so minimal that the two terms are virtual synonyms, interchangeable for the sake of his metrics. ... Differences between father figures just did not matter that much yet in Anglo-Saxon England, a situation reinforced by everyday life, where grandfathers, fathers, uncles, brothers, and their male progeny ate, worked, fought, and attended meetings ... Goody interprets such blurring of some distinctions and sharpening of others as a function of the universal incest taboo, a determining factor in kinship arrangements." – Talia Ford Sep 15 '13 at 1:27
  • @Medium, some languages are more realistic than others with kinship terms, and others are just insane. Consider, for example, the perplexingly intricate system of Chinese kinship terms where 襟弟 jīndì means either “wife’s younger brother’s husband” or “wife’s [younger or older] brother’s husband if he is younger than me”, and 族妹 zúmèi is either “great-granddaughter of your paternal great-grandfather’s younger brother”, or “great-granddaughter of your paternal great-grandfather’s [younger or older] brother, if she is younger than me”. English just falls at the other end of the spectrum. – Janus Bahs Jacquet Mar 26 '14 at 22:14
  • @JanusBahsJacquet Chinese is indeed on the other end of the spectrum compared to English! Just to confirm - did you mean "wife’s younger brother’s husband" or is it a term for "wife’s younger brother’s partner"? – MediumOne Mar 27 '14 at 7:55

No, there is no word for it in English.

I disagree with Edwin Ashworth and the Wikipedia article he quotes (which is entirely unreferenced). I would neither use nor normally understand brother-in-law to include a wife's sister's husband in modern English.

I would not be surprised to come across that usage in older writing (before the 20th century): many kinship terms were formerly used less precisely than today.

The OED says "Sometimes extended to the husband of one's wife's (or husband's) sister", but that entry has not been revised since 1888.

It is strange, and sometimes inconvenient, that there is no word.

  • 4
    In my neck of the woods, it's quite common to refer to all the relatives-of-relatives of your own generation as "in-laws". In fact, I will sometimes call my sister's husband's sister my "sister-in-law". I do balk at extending that to said sister's husband's sister's husband, though. (Thankfully, they live on the other side of the pond, so I don't have too much occasion to try to refer to them by anything other than name.) – Marthaª Oct 26 '12 at 16:36
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    @Colin Fine: broth·er-in-law (brr-n-lô) n. pl. broth·ers-in-law (brrz-) 1. The brother of one's spouse. 2. The husband of one's sister. 3. The husband of the sister of one's spouse. The American Heritage® Dictionary of the English Language, Fourth Edition copyright © 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. – Edwin Ashworth Nov 29 '12 at 21:49
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    I stand corrected. It is outside my experience - perhaps a UK/US difference? – Colin Fine Dec 2 '12 at 11:21
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    My wife says her sister's husband is my-brother-in law, and we're in the UK. And I never argue. ( :-) ) To be honest, it's easier calling him Peter. – Edwin Ashworth Dec 2 '12 at 22:46

"Brother/sister-in-law" is common U.S. English usage to refer to the spouses of your spouse's siblings. I have four brothers-in-law -- my sister's husband, my husband's brother, and my husband's sisters' husbands. And, I have three sisters-in-law - my husbands two sisters, and his brother's wife.


I would call the man "my wife's brother-in-law." He's her brother-in-law, not yours.

  • 1
    An equivalent would be "my sister-in-law's husband". Actually, no - that is ambiguous. That relationship could also describe my brother! Oh wait (again), so could "my wife's brother-in-law"! So these are equivalent. I would suggest which you use would depend on whether you want to emphasis the spousal part of the relationship or the fraternal part of the relationship. – psion5mx Mar 19 '14 at 12:02
  • @Tom Au You'll excuse me if I choose to take the authority of AHD over your assertion. – Edwin Ashworth Mar 26 '14 at 22:20

Definition of co-brother:

Sister in law's (wife's sister) husband.

Ref: http://www.collinsdictionary.com/submission/1213/co-brother

  • Ah! this is request to include the word into dictionary it is not already present. – Shiva Sep 10 '18 at 14:02

Co-brother-in-law or simply co-brother



That is the word you are looking for; because brother-in-law is strictly used for brothers of spouse I present this variation in this part of the world.

Bit of context, in India we are very precise with relationship. And so brother-in-law cannot replace cousin-in-law; this word co-brother came into existence to denote the person marries sister of the wife (being gender neutral is tough).

Reference :


The answer to this can be viewed from a logic process. The sibling of a spouse is by relation the brother or sister of the spouse, and by marital assignment the brother or sister - in - law to the spouses marriage partner. The spouse of one of those siblings can not accurately be given the term brother or sister in law as well, as the terminology usage creates a brother / sister relationship to the spouses sibling and their respective marital partner.

  • It's rarely a good idea to apply logic to language in this way. – phoog Sep 30 '14 at 3:42

protected by Andrew Leach Jul 25 '14 at 10:58

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