phlegm vs impassivity

phlegm and impassivity both are nouns.

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

As nouns, phlegm and impassivity are synonyms defined as:

phlegm and impassivity: apathy demonstrated by an absence of emotional reactions

Other synonyms of phlegm include emotionlessness, impassiveness, indifference, stolidity, unemotionality.

phlegm (noun)	impassivity (noun)
inactivity; showing an unusual lack of energy	apathy demonstrated by an absence of emotional reactions
expectorated matter; saliva mixed with discharges from the respiratory passages; in ancient and medieval physiology it was believed to cause sluggishness
apathy demonstrated by an absence of emotional reactions