For example:

  1. I have a sister named Charlotte.
  2. Charlotte is married to Martin.
  3. Martin has a brother named William.

Martin is my brother-in-law, but what is William to me?

  • 1
    Maybe ask at Genealogy & Family History? Commented May 26, 2013 at 18:24
  • 2
    I'm afraid there is no commonly used name for that connection. Normally, you would say "my brother in law's brother". If you and William are very close, I suppose you could call him "my brother in law" in casual conversation, or just "a friend". Commented May 26, 2013 at 18:36
  • 2
    Just say "brother-in-law" unless there is some reason that a more precise relationship is needed.
    – GEdgar
    Commented May 26, 2013 at 18:58
  • 1
    Smells like a duplicate, but I don't have time to search for it...
    – Drew
    Commented May 27, 2016 at 20:35

1 Answer 1


As you have been told on Genealogy & Family History, there is no "technical term" for the relationship you describe.

In most areas of language you select the words used to suit the purpose you wish to achieve. If my sister's husband has two brothers, then

  • the one in jail is her brother-in-law.
  • the famous rock star is related to me by marriage, almost a brother.

Not the answer you're looking for? Browse other questions tagged or ask your own question.