frestus Share definition Flag Noun.A term used to describe the excess film, usually food, on a jar/lid/pot. Person 1: what is that white crusty stuff on the milk cap?Person 2: oh, that’s just the frestus. frestus by Ashley Bonney March 14, 2019 0 0 Get merch Get the frestus mug. Buy Now — $32.95 See more merch