usually used to describe 1) a chill, outgoing, or edgy person or 2) a fresh or novel idea, phrase, outfit, or gadget.
1) OMG he just gave a piggy back ride to that crippledgirl so she didn't have to use crutches..he is SO rouche.
2) Our new lunch hangout is so rouche and secluded...we call it the clubhouse
n: A promiscuous person, usu. a promiscuous female. See "slut", etc.
More commonly used in the 1950's, this term has fallen into general disuse, but may still be heard in fiction that takes place in that era, or in circles that consider retro-talk cool.
"I wouldn't trust that little roundheels as far as I could throw her."