staleness vs must

staleness and must both are nouns.

Word	Noun	Adjective	Verb	Adverb
staleness	Yes	No	No	No
must	Yes	Yes	No	No

As nouns, must is a hyponym of staleness; that is, must is a word with a more specific, narrower meaning than staleness:

Other hyponyms of staleness include moldiness, mustiness.

staleness (noun)	must (noun)
having lost purity and freshness as a consequence of aging	the quality of smelling or tasting old or stale or mouldy
unoriginality as a result of being dull and hackneyed	grape juice before or during fermentation
	a necessary or essential thing

staleness (adjective)	must (adjective)
	highly recommended