Acronym: Bulbus, Wet, Meaty, Pussy.
A word used to descibe specific features of the female genitalia. This would include the general "mound" shape including inner and outer labia. Usually, a bwmp is rather chubby with big lips, big clit and very wet when handled.
Look at Rachael, damn, judging by her camel toe in those panties I'd bet the farm she's got mad bwmp.