See nub in Webster's New World Roget's A-Z Thesaurus II
noun
An unevenness or elevation on a surface:
bump, hump, knob, knot, lump1, protuberance. See convexThe most central and material part:
core, essence, gist, heart, kernel, marrow, meat, pith, quintessence, root1, soul, spirit, stuff, substance. (Law) gravamen. See be
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