THESAURUS
underbelly
abdomen, abomasum, bay window, bed, bedrock, beerbelly, belly, bottom, bottom side, breadbasket, breech, buttocks, craw, crop, diaphragm, downside, embonpoint, first stomach, fundament, gizzard, gullet, gut, hardpan, honeycomb stomach, kishkes, lower side, lowest layer, lowest level, manyplies, maw, midriff, nether side, nethermost level, omasum, paunch, pot, potbelly, potgut, psalterium, pusgut, rennet bag, reticulum, rock bottom, rumen, second stomach, spare tire, stomach, substratum, swagbelly, third stomach, tum-tum, tummy, underlayer, underneath, underside, ventripotence