involuntariness vs disposition

involuntariness and disposition both are nouns.

Word	Noun	Adjective	Verb	Adverb
involuntariness	Yes	No	No	No
disposition	Yes	No	No	No

As nouns, disposition is a hypernym of involuntariness; that is, disposition is a word with a broader meaning than involuntariness:

Other hypernyms of involuntariness include temperament.

involuntariness (noun)	disposition (noun)
the trait of being unwilling	the act or means of getting rid of something
	your usual mood
	a natural or acquired habit or characteristic tendency in a person or thing
	an attitude of mind especially one that favors one alternative over others