X  : Is there a word like co-brother?

• SVK : I have come across many people , mainly from south India, using the word ‘Co-brother’ to mean ‘ the husband of one’s wife’s sister.  If there were a word like co-brother, there should be a word like ‘Co-sister’ to mean the feminine gender.  I haven’t come across people using the word ‘co-sister’.  The following dictionaries will enlighten you on the matter with more details.
• 1.  Oxford Advanced Learner’s Dictionary of Current English.
• 2.  Longman Dictionary of Contemporary English.
• 3.  Cambridge International Dictionary of English.
• 4.  Collins Cobuild English Language Dictionary.

I would recommend the above Dictionaries because they are my favourite ones and I have been using them for decades.  I was not able to find the word ‘Co-brother’ in any of the above language dictionaries.  I don’t depend on online interpretations beyond a limit because of lack of authentication from accredited language scholars.  I am afraid that the English people do not use the word ‘co-brother’.  As far as I know there is no lexical, academic or University accreditation for the word ‘ co-brother’. The Dictionaries herein mentioned  use ‘ brother-in-law’, ‘sister-in-law’ etc as the case may be to refer to the word at question.

When we consider the usage in vogue at least in some parts of India, I suppose that the word ‘co-brother’ may be accepted by language authorities in future.  If it has not been accepted by now, such a word will have to be considered as non-existent.

A :  How do you suggest a way to consider the so-called word ‘co-brother’?

• SVK :  The various languages across the globe are undergoing tremendous changes and additions owing to the growth and influence of various branches of knowledge.  In this course, some words become obsolete and some other words crop up.  And these changes are accredited by appropriate language authorities in consultation with the subject experts in due course.  And it is the natural sequence of growth.  But overnight changes cannot be expected to take place in the case of language development.  Evolutionary changes preponderate over revolutionary changes in the path of language history.
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•   To sum up , I think you can selectively use this particular word in such circles where it has a common acceptance for communicative or spoken purposes.  However while writing , an errorless and authoritatively acceptable style may be more appropriate.