Your midriff is the front of your body between the chest and the waist — the stomach area you see from the outside, not the organs inside. Clothes talk uses it a lot: a crop top bares the midriff. The word is a little old, or magazine-like; younger people more often say stomach, belly, or just waist. It is not quite the same as waist: the waist is the line where a belt sits, and the midriff is the soft stretch above it, up toward the ribs. Though actually, in very old English it also named the muscle under the lungs, the one that helps you breathe, because that sits in the middle of the trunk. The second half of the word, riff, is an old word for the belly. It is not the music word riff, which only sounds the same.