whimsy vs irresponsibility

whimsy and irresponsibility both are nouns.

Word	Noun	Adjective	Verb	Adverb
whimsy	Yes	No	No	No
irresponsibility	Yes	No	No	No

As nouns, irresponsibility is a hypernym of whimsy; that is, irresponsibility is a word with a broader meaning than whimsy:

whimsy: the trait of acting unpredictably and more from whim or caprice than from reason or judgment
irresponsibility: a form of untrustworthiness; the trait of lacking a sense of responsibility and not feeling accountable for your actions

Other hypernyms of whimsy include irresponsibleness.

whimsy (noun)	irresponsibility (noun)
the trait of acting unpredictably and more from whim or caprice than from reason or judgment	a form of untrustworthiness; the trait of lacking a sense of responsibility and not feeling accountable for your actions
an odd or fanciful or capricious idea