inactivity vs phlegm

inactivity and phlegm both are nouns.

Word	Noun	Adjective	Verb	Adverb
inactivity	Yes	No	No	No
phlegm	Yes	No	No	No

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

inactivity (noun)	phlegm (noun)
being inactive; being less active	inactivity; showing an unusual lack of energy
a disposition to remain inactive or inert	expectorated matter; saliva mixed with discharges from the respiratory passages; in ancient and medieval physiology it was believed to cause sluggishness
the state of being inactive	apathy demonstrated by an absence of emotional reactions