UAMF Share definition Flag Ugly Ass Mother Fucker. This word can be used to anyone you have anger for or think is really ugly. My ex-boyfriend is a total UAMF! Your cousin is a UAMF. Or you can bluntly say it "UAMF" UAMF by Rianna D. A. Corby April 19, 2007 0 0 Get merch Get the UAMF mug. Buy Now — $32.95 See more merch