the point, gist, or heart of something.

a knob or protuberance.

a lump or small piece

a nub of coal; a nub of pencil.

a small mass of fibers produced on a card, dyed brilliant colors, and introduced into yarn during the spinning process.

noun

exterior , outside

noun

basic , bottom line * , crux , essence , heart * , kernel , meat * , meat and potatoes * , nitty-gritty * , nubbin , nucleus , pith , point , short , substance , upshot , bulge , knob , lump , node , protuberance , swelling , hump , knot , core , gist , marrow , meat , quintessence , root , soul , spirit , stuff , (colloq.) knob , bump , excrescence , jag , snag