What word could I use to define someone who is not kin to me but I regard to be better than a friend?

  • 1
    There's really nothing wrong with "close friend".
    – Hot Licks
    Commented Jul 19, 2015 at 11:33

7 Answers 7


What about:

bosom buddy

A very close friend


A close or good friend. An intimate. A bosom friend.
An intimate friend who is not a blood relation...



There are only idioms for such a thing.

  • Thick as thieves
  • Brother from another mother
  • Like brothers (as in, we're like brothers)
  • Soul brother

I have plenty of friends whom I've known since we were born and I have yet to come across a single word that can sum up the idea of being "like brothers"... Most of the time, I just say "We might as well be brothers"


My "best friend", "BFF", "closest [dearest] friend", or my "blood brother"

BFF /ˌbiː.efˈef/
The initialism (or abbreviation) for Best Friend Forever
a way of referring to a person's best friend

Blood brother

Blood brother can refer to one of two things: a male related by future birth, or two or more men not related by birth who have sworn loyalty to each other. This is in modern times usually done in a ceremony, known as a blood oath, where having each person make a small cut, usually on a finger, hand or the forearm, and then the two cuts are pressed together and bound, the idea being that each person's blood now flows in the other participant's veins. In modern times, some gangs have also been rumored to make blood pacts.

See Cambridge Dictionary for a very similar, but less detailed definition than Wikipedia's.
(There are some users who turn up their noses at Wikipedia)

  • 1
    *BFF BBF would be big beautiful friend
    – Jimmy
    Commented Jul 20, 2015 at 15:39
  • @Jimmy oh, thanks, you're a pal. Word blindness struck again.
    – Mari-Lou A
    Commented Jul 20, 2015 at 16:33
  • No biggie @Mari-Lou A
    – Jimmy
    Commented Jul 20, 2015 at 17:36

A confidant (or, if female, sometimes confidante) is defined by Merriam-Webster as "a trusted friend you can talk to about personal and private things".


Two phrases are used:




  • bosom buddy and cater-cousin were already suggested by Jonny 5
    – Mari-Lou A
    Commented Jul 21, 2015 at 5:26
  • I did not see his answer on my browser when I responded to the OP, as a matter of fact the answers were actually edited in at 7:48 even though the question was started at 7:37. Having said that, who cares? Commented Jul 23, 2015 at 18:31
brother from another mother

    a good friend that is more like a brother. Also sister from another mister.

        He's my brother from another mother.


Which is weird since actual half brothers could literally be brothers from different mothers.


You can use:

-bosom friend

-partner in crime

-twin brother

-partner for life

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