tremolo vs quiver

tremolo and quiver both are nouns.

Word	Noun	Adjective	Verb	Adverb
tremolo	Yes	No	No	No
quiver	Yes	No	Yes	No

As nouns, quiver is a hypernym of tremolo; that is, quiver is a word with a broader meaning than tremolo:

tremolo: (music) a tremulous effect produced by rapid repetition of a single tone or rapid alternation of two tones
quiver: a shaky motion

Other hypernyms of tremolo include palpitation, quivering, shakiness, shaking, trembling, vibration.

tremolo (noun)	quiver (noun)
vocal vibrato especially an excessive or poorly controlled one	the act of vibrating
(music) a tremulous effect produced by rapid repetition of a single tone or rapid alternation of two tones	case for holding arrows
	an almost pleasurable sensation of fright
	a shaky motion

tremolo (verb)	quiver (verb)
	shake with fast, tremulous movements
	move with or as if with a regular alternating motion
	move back and forth very rapidly