knob (n.) Look up knob at Dictionary.com
late 14c., knobe, probably from a Scandinavian or German source (compare Middle Low German knobbe "knob," Middle Dutch cnoppe, Dutch knop, Old Frisian knopp, knapp, Old High German knopf, German Knopf "button," Old Norse knyfill "short horn"). Meaning "knoll, isolated round hill" is first recorded 1640s, especially in U.S.