I would like to know what someone could call the women whose husbands are biological brothers? It isn't sisters-in-law of course, nor wives-in-law!
Can someone help? I am in total confusion.

  • 1
    If woman W married man M who has (biological) brother B, then B's relationship to W is brother-in-law and W's relationship to B is sister-in-law. If that's not what you're looking for, please edit your question to clarify. Add examples.
    – Dan Bron
    Jun 16, 2017 at 14:03
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    If two brothers are married, their wives are sisters-in-law to each other, even though they may look like they are an extra step removed. Each wife is of course a sister-in-law to her husband's brother. Jun 16, 2017 at 14:42
  • As a note, there's no such term as wife-in-law; sister-in-law is good for the wife of my brother or for the sister of my spouse. Also, for what is asked for here but that is in an answer below.
    – Mitch
    Jun 19, 2017 at 17:43
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    It would be helpful to know why you think "it isn't sisters-in-law of course," because in most Englishes (particularly American and British), it is.
    – Andrew Leach
    Jun 21, 2017 at 7:19
  • 1
    Please add the Indian English tag, if you were also interested in that dialect.
    – Mari-Lou A
    Jun 21, 2017 at 7:46

3 Answers 3


Answer: co-sisters.

Explanation: In Indian English, two men are called "co-brothers" if they are married to two women who are sisters.


So I suppose co-sisters would describe the two women in your case, although this term is specific to Indian English and I am not sure whether it is commonly used even in India:

CAMBRIDGE English dictionary defines co-sister as


the wife of your husband's brother


I am writing a more detailed answer because I realised these terms are specific to Indian kinship relations and possibly unfamiliar to native speakers of English worldwide:

The term ‘co-brothers’ is more common because it's a special relationship explicitly defined with an English neologism (coined over 100 years ago to refer to men 'newly related by marriage' after marrying two or more women who are sisters by birth) — co-sisters is an exact-parallel term derived from it.

In previous generations, there were large families in India, and today there are families with 5 or 6 sisters whose husbands are all co-brothers of each other — although living apart and technically members of different (their own patrilineal) families, co-brothers were typically closely bound by friendship and obligated to help and support each other.


BOSS: Why you are going on leave? (INDIAN ENGLISH)

Mr.Gopal: I need to go and be with Mr.Krishnan, who is having his appendix removed.

BOSS: How you are related?

Mr.Gopal: I and Mr.Krishnan are co-brothers.

On the other hand, co-sisters traditionally lived together in the same joint-family household of their husbands and 'worked together' under the direction of the mother-in-law. In the Indian context of mostly patriarchal joint-families, no special term was needed for women (now called co-sisters), who technically belonged to the same (marital) family and were grouped together as sisters-in-law in the meaning of daughters-in-law of the same household. So 'co-sisters' is a less commonly used term (more relevant only recently with the increasing prevalence of geographically separated nuclear families) derived from 'co-brothers.' Modern Example:

Mrs.A: I came to know only recently from facebook that you are related to that TV star Mrs.C...

Mrs.B: yes, Mrs.C and I are co-sisters.

Mrs.A: OMG! but why I have never seen you together? (INDIAN ENGLISH)

Mrs.B: That's because she lives in India and we live in the USA!

Note too that there is no special term for this type of relationship (and so the equivalent term is the more generic brothers-in-law // sisters-in-law, as already mentioned in the previous answers and comments) in American and British English.

  • Thanks! That clarifies it for me. +1. Unfortunately, that's not what it is in AmE or BrE. Despite its rather low frequency in the usual AmE/BrE society, it's not a 'special' situation requiring a special name. Also, this labels the pair of women from the outside. In AmE/BrE, the expectation is the relation from one woman to the other, ie a woman A has a husband, he has a brother, and the brother has a wife B, A calls B her ... what? Would it be co-sister? In AmE/BrE B would b called A's sister-in-law.
    – Mitch
    Jun 19, 2017 at 17:25
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    @Mitch a pair of brothers do not necessarily marry a pair of sisters of another family but it is not uncommon in India. We also have the so-called exchange marriage whereby Mr.A marries Ms.B and Mr.A's sister marries Ms.B's brother. Most Indian communities are patriarchal and patrilineal, so a woman traditionally leaves her family of birth and 'officially gets transferred' to her husband's family. I recently wrote a detailed answer / comment at Quora which was related to cousin marriage but also explains this phenomenon. I SHALL find that too and link it here. Jun 19, 2017 at 17:36
  • Paucity of words for relationships is the thread you're thinking of
    – Mitch
    Jun 19, 2017 at 17:39
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    This is actually Not An Answer, because the question specifically (via tags) asks for American English and British English, and your answer is exclusively about Indian English.
    – Andrew Leach
    Jun 21, 2017 at 7:20
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    @AndrewLeach if the OP wanted to know exclusively about AmEng and brEng why did he then accept this answer? He accepted it because he realized that the term co-sister is more appropriate in Indian English, and English Student explained very well why and how it originated. It's an original answer, an answer you won't find in a dictionary or in Wikipedia, we should be encouraging users to write their experiences not copy and paste answers.
    – Mari-Lou A
    Jun 21, 2017 at 7:31

The wife of your husband's brother would be your sister-in-law:


  • 2b: the wife of one's spouse's sibling



Consider the following family tree, where M1 and M2 are male siblings (brothers). They both get married (to two women, very traditional).

     |     |
F1 x M1    M2 x F2


  • F1 calls M2 her brother-in-law and F2 her sister-in-law
  • F2 calls M1 her brother-in-law and F1 her sister-in-law
  • M1 calls F2 his sister-in-law
  • M2 calls F1 his sister-in-law

note: This answer completely ignores the usage of co-brother / co-sister since, as far as I know, that is quite specifically Indian English. The question was tagged to ask about American and British English, notwithstanding the (imho surprising) fact that the answer for Indian English was accepted.

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    @Mari-LouA It is cited in an English dictionary, as Indian English. Now, I'm the first to acknowledge InE as real English, but this seems like asking for the spelling of "labour", asking specifically about British English, and accepting "labor" as the answer. If one is looking for an Indian English answer, one should specify that. I actually added my remark to my answer expecting (in vain?) the OP to follow your advice to add the InE tag.
    – oerkelens
    Jun 22, 2017 at 17:43
  • The OP didn't specifically say within the question that he was looking for BrEng or AmEng, those were the tags that he or she used in their first ever question (which is a pretty good first time effort). And you and I know that newcomers often misuse tags, or do not know how to tag their questions properly. BTW your answer basically repeats Hank's, and lacks any reference.
    – Mari-Lou A
    Jun 22, 2017 at 17:55
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    Tags are part of the question in absence of explicit mention in the question text itself. And yes, I repeat an answer that was posted as I was drawing a picture to clear things up a bit. I have no problem removing my answer if you really think it is superfluous, but some people like pictures to make things a bit clearer.
    – oerkelens
    Jun 22, 2017 at 17:59

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