offensive slang A derogatory term for someone who is fat or obese. I look like a real fatso in this skimpy bikini, don't I?Hey fatso, why don't you pick on someone your own size?
fatso
(ˈfætso)
n. a fat person. (Cruel. Also a rude term of address.) Some fatso tried to get on the plane and couldn’t even get through restroom the door!