A small fraction of the buttock cleft (butt crack) so slightly exposed that it looks more like a dent then a full crack. Most commonly seen on females when sitting down in low rise jeans or shirtless males wearing saggy pants or board shorts.
Guy 1: Damn, Kelsey has the nicest ass! Today in chemistry you could totally see her butt crack when she sat down!
Guy 2: Yeah she does, but you could only really see her butt dent.
Girl 1: Ew, I can see that old guys butt dent in front of us! His wife need's to buy him a belt.
Girl 2: Sick. Thank god its just the Dent and not the whole crack.