Closely related words from the same etymology mean "tail, end; adherent, follower" and "to follow". Hebrew זָנָב (zanáv, "tail") is also related.
According to my dictionary - "dhambi" has no plural and belongs to cl. 9/10 N-N
A cursory search of "dhambi" (with the quotes) on Google gives many results, although my Swahili is not good enough to verify/inspect them.
However, http://www.goswahili.org/dictionary/ and http://africanlanguages.com/swahili/ do list dhambi under noun class 9/10, and logically it should be so since its an Arabic loanword (or are there exceptions? please correct me if I'm wrong) Anyone can share more on this?