Meaning

noun a small lump or protuberance

noun a small piece

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

originEither directly from Middle Low German, or from knub, from a Middle Low German word (compare Low German Knubbel, Knobbel (“knot; lump”)). Compare knob.

Etymology from Wiktionary, CC BY-SA 3.0