shakiness vs instability

shakiness and instability both are nouns.

Word	Noun	Adjective	Verb	Adverb
shakiness	Yes	No	No	No
instability	Yes	No	No	No

As nouns, instability is a hypernym of shakiness; that is, instability is a word with a broader meaning than shakiness:

Other hypernyms of shakiness include unstableness.

shakiness (noun)	instability (noun)
the quality of being unstable and insecure	the quality or attribute of being unstable and irresolute
a shaky motion	unreliability attributable to being unstable
	an unstable order
	a lack of balance or state of disequilibrium