An
employee of a
university whose ostensible purpose is to be a
parent figure to a floor of building of
coeds living in a
dormitory or
residence hall. Usually an
RA gets free room and board in exchange for preserving order and being a person students can go to when they have problems.
It's possible that sometimes an RA is using his or her social status to seduce younger coeds, but such rumors are completely unsubstantiated.