jumbutt Share definition Flag n. The sagging lower region of belly fat that overhangs obese women's genitals. Also known as a FUPA. Person 1: That old lady has the biggest jumbutt I think I've ever seen. Person 2: Yikes! jumbutt by chomski January 5, 2012 0 0 Get merch Get the jumbutt mug. Buy Now — $32.95 See more merch