The round end of a blacksmith hammer, typically used for "peening over" the sides of a protruding rivet.
Bro, I totally used my peen to round the end of my rivet, after hammering it into the hole with the head of my ball-peen hammer.
by Pein man November 05, 2019
PeenKing, Peen has a honey-like smooth voice and a long ass green tongue. Serves do missions for peen and love peen. PeenIs nice to serves nice to him.
by Nochuwu September 16, 2018
Having unprotected sex before you should which results in getting pregnant as a teen, making you a peen.
by P.B Bloomfield February 09, 2019
by cryxtaltears August 16, 2019