Indians especially have a tendency to use the terms co-son-in-law and co-sister-in-law while referring to relations.
- The husband of one's wife's sister is called Co-son-in-law.
- The wife of one's husband's brother is called co-sister-in-law.
While introducing the relations to others they are called so.
The terms may be understood in the Indian sub-continent. But such terms are not understood by the native speakers.
I searched on the internet for the equivalent terms in English but I could not find them.
I here with attach two links so that you may understand what I mean:
“Co-brother” or “co son-in-law?”
https://en.m.wiktionary.org/wiki/co-sister-in-law
What are the equivalent terms used by the native speakers while introducing them (the mentioned relatives) to others?
Best Answer
In US English (and likely most non-India regions), we refer to these persons as simply brother-in-law or sister-in-law. My wife has a sister, and that sister is married. I refer to both husband and wife as my brother and sister-in-law.
In the same way, my mother has a brother who is married. I refer to both husband and wife as my aunt and uncle. In both cases the spouse becomes referred to as the same relationship. We would know from the social context that "aunt and uncle" refer to wife and husband rather than brother and sister, and we would therefore know that only one is a blood relation. In the same way, when "brother and sister-in-law" refer to a married couple, we know the actual relationships.
EDIT: The expression "co-son-in-law" would seem to contradict US English usage. Brother/sister-in-law refers to someone of the same generation as yourself. Son/daughter-in-law refers to someone of the same generation as your child and NOT the same generation as yourself. My daughter's husband is my son-in-law, so I would have expected co-son-in-law to mean something similar. But I gather it does not!
SECOND EDIT: It's clear from the surrounding discussions that regional usage varies. There are differences depending whether the speaker's intent is to identify a person, a married couple, or a blood relationship. My own usage (which, by definition, is regional) is not the same as what's familiar usage to others here.