From Longman Dictionary of Contemporary Englishnubnub /nʌb/ noun 1 → the nub of the problem/matter/argument etc2 [countable] a small rounded piece of something, especially a piece that is left after the rest has been eaten, used etc
Examples from the Corpus
nub• The baby clutched a nub of carrot.• Then the Sheikha took her needle and drove it up through the middle of the quarter-inch nub, anchoring the fabric.• I was just waiting for the discussion to get down to the real nub of things.• Interpersonal skills form the nub of the trainers' course.• And that's the nub of it.• Here we come to the nub of it.• The nub thereof is, of course, that you must first get to know your heron.• Speed is of no consequence, but duration is vital, the very nub of the matter.• The cat shifted about on his lap, clawed at the woolen nubs of his trousers.Origin nub (1500-1600) Probably from Low German knubbe 