unsteadiness vs unregularity

unsteadiness and unregularity both are nouns.

Word	Noun	Adjective	Verb	Adverb
unsteadiness	Yes	No	No	No
unregularity	Yes	No	No	No

As nouns, unregularity is a hypernym of unsteadiness; that is, unregularity is a word with a broader meaning than unsteadiness:

unsteadiness: the quality of being unsteady--varying and unpredictable
unregularity: not characterized by a fixed principle or rate; at irregular intervals

Other hypernyms of unsteadiness include irregularity.

unsteadiness (noun)	unregularity (noun)
the quality of not being steady or securely fixed in place	not characterized by a fixed principle or rate; at irregular intervals
the quality of being unsteady--varying and unpredictable