nub, nubble(noun)

a small lump or protuberance

nub, stub(noun)

a small piece

"a nub of coal"; "a stub of a pencil"

kernel, substance, core, center, centre, essence, gist, heart, heart and soul, inwardness, marrow, meat, nub, pith, sum, nitty-gritty(noun)

the choicest or most essential or most vital part of some idea or experience

"the gist of the prosecutor's argument"; "the heart and soul of the Republican Party"; "the nub of the story"

Nub(verb)

to push; to nudge; also, to beckon

Nub(noun)

a jag, or snag; a knob; a protuberance; also, the point or gist, as of a story