A crop top (also cropped top, belly shirt, half shirt, midriff shirt, midriff top, tummy top, short shirt, and cutoff shirt) is a top, the lower part of which is high enough to expose the waist, navel, or some of the midriff. The cropping of a top in this manner is more popular among females but have since grown as a fashion trend for men as a comeback from the 80's. Bikinis and sports bras are generally not regarded as crop tops. (source)