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Whereas, cleavage implies the top view of a woman's breast, "neathage" implies the bottom view. This is usually accomplished by a female wearing a small shirt, or lifting up her shirt so that not only her abdominal is exposed, but also the bottom of her breasts. Neathage is also possible when a girl has a hand bra, covering the nipples but exposing her cleavage and neathage.

See also: under boob
Dude 1: Yo did you see that chick?
Dude 2: You mean the hot one wearing a baby GAP shirt?
Dude 1: Yeah man you could see her neathage!
Dude 2: Hell yeah dude!
by implicit March 28, 2008
The underside of a woman's brests when she wears a shirt cut up to the bottom of them.
Wow! If that girl wore her shirt and higher, her neathage would be showing her nipples
by AEron November 07, 2003