Slang term, from the county of Wexford, Ireland:
1. Space between the balls and arse (may be used to refer to the same space of the female gender irrespective of the practical absence of a scrotum)
2. Term of abuse.
2.'You may kiss my dead uncle's barse'
The barse is a relatively useless part of the body, a bit like the appendix, and is paid little to no attention until you get barse rash.