The Rice University Neologisms Database

Pectorals that resemble women’s breasts Moobs are man boobs, or rather, they are the pectorals of obese men. The term moobs is used when the men’s pectorals begin to resemble the women’s breasts. Often, the men have to be morbidly obese to have moobs. If a man is slightly out of shape, he does not have moobs; a man only has moobs when his pectorals are actually quite large. The blend moobs (man + boobs) easily brings to mind the image of man boobs; thus, the meaning of this term is not very hard to comprehend. Furthermore, the term sounds very juvenile, and thus is commonly used by teenagers.