knob vs ornament

knob and ornament both are nouns.

Word	Noun	Adjective	Verb	Adverb
knob	Yes	No	No	No
ornament	Yes	No	Yes	No

As nouns, ornament is a hypernym of knob; that is, ornament is a word with a broader meaning than knob:

Other hypernyms of knob include decoration, ornamentation.

knob (noun)	ornament (noun)
a round handle	something used to beautify
a circular rounded projection or protuberance
an ornament in the shape of a ball on the hilt of a sword or dagger
any thickened enlargement

knob (verb)	ornament (verb)
	make more attractive by adding ornament, colour, etc.
	be an ornament to