means A rounded lump, handle, or control — the kind you turn, pull, or push on doors, drawers, dials, and devices.

from From Middle English 'knobbe,' a rounded lump or bump, likely borrowed from a Low German or Middle Dutch source (compare Middle Low German 'knobbe,' a knot or knob). It sits in a whole family of blunt, lumpy English 'kn-' words — knot, knuckle, knur — that share that satisfying sense of something rounded and protruding. The 'k' was once spoken aloud, before English quietly stopped pronouncing it and left the silent letter behind like a forgotten handle.