THESAURUS
nub
axiom, axis, bench mark, bilge, blain, bleb, blister, blob, boss, bow, bubble, bulb, bulge, bulla, bump, bunch, burl, button, cahot, cardinal point, center, center of action, center of gravity, centroid, centrum, chief thing, chine, climax, clump, condyle, convex, core, cornerstone, crisis, critical point, crux, dead center, distillate, distillation, dowel, ear, elixir, epicenter, essence, essential, essential matter, fabric, feel, finish, flange, flap, flower, focus, fundamental, gall, gist, gnarl, grain, granular texture, gravamen, great point, handle, heart, high point, hill, hub, hump, hunch, hypostasis, important thing, indentation, inner essence, issue, jog, joggle, kernel, keystone, knob, knot, knub, knur, knurl, landmark, lip, loop, lump, main point, main thing, marrow, material, material point, matter, meat, medium, medulla, metacenter, middle, milestone, mole, mountain, nap, nave, navel, nevus, nubbin, nubble, nucleus, nuts and bolts, omphalos, papilloma, peg, pile, pit, pith, pivot, pock, postulate, principle, protuberance, quid, quiddity, quintessence, real issue, rib, ridge, ring, salient point, sap, shag, short, shoulder, sine qua non, soul, spine, spirit, storm center, structure, stud, stuff, style, substance, substantive point, sum and substance, surface, surface texture, tab, texture, the bottom line, the nitty-gritty, the point, tubercle, tubercule, turning point, umbilicus, upshot, verruca, vesicle, wale, wart, weave, welt, woof