The ABC and CEDICT both say 俱樂部 (ju4le4bu4) is a loan word for club/group/organisation.

Does anyone know in which language or word it might be a loan word from?

It's from English "club", but from Japanese. Here's what Maksym had to say about 倶 now carrying that meaning by itself in Japanese after noticing that this was also loaned to Chinese through Japanese:

"Aaah! I found it now!

http://en.wikipedia.org/wiki/Ateji

For 倶, the "social club" meaning comes from 倶楽部, which was an old ateji way of writing club, like night club. In Japanese the characters each have several readings, but cherry-picking them produces ku, ra and bu, coming together to make kurabu, which is as close as it can get to club.

Apparently Chinese took the characters without much regard for their Chinese phonetic values, which make ju4le4bu4, thanks to the well known k/g->q/j shift. The fact that it's gurabu as would be expected from just k->j is a reflection of the wonderful phonetics of middle chinese :)"

More from that Wikipedia article:

"When using ateji to represent loanwords, the kanji are sometimes chosen for both their semantic and phonetic values, a form of phono-semantic matching. A stock example is 倶楽部 (kurabu) for "club", where the characters can be interpreted loosely in sequence as "together", "fun" and "place"."

Neat, thanks!!

Sometimes I wish the dictionaries kept extra information about how words got into them. I hope one day cc-cedict will get some enhancements to how it tracks and stores things (:

That'll certainly help me remember that word!