O.A.P. Share definition Flag Someone who is old and putrid. Generally the old hag living opposite. Yuck, that women is ancient and smells like rotting dead people. Yep she must be an O.A.P. Old Aged Pensioner O.A.P. by fghjklm October 21, 2010 0 0 Get merch Get the O.A.P. mug. Buy Now — $32.95 See more merch