A fork of Rural Dictionary
The amalgamation of "masterpiece" and "ass" - essentially a masterful ass. This is applicable to any female that has a lot to bare with her derrière.
Jessica Biel has an ass that won't stop! What an assterpiece!
Even in her older state, J Lo still has a mighty fine assterpiece protecting her backside.
the wonderful paintjob that one gives the toilet when they have explosive diarreah
I painted such an assterpiece today that I thought I was Michaelangelo.