Определение co-brother-in-law в Английский Язык Английский Язык словарь
one's wife's sister's husband; or more generally one's spouse's brother-in-law, the brother of one spouse in relation to the siblings of the other spouse
in plural The relationship between men who marry sisters.
one's brother-in-law or sister-in-law's brother; that is, one's sibling's spouse's brother (one's sister's husband's brother or one's brother's wife's brother)
in plural The relationship between men whose brother and sister are married to each other.