emotionlessness vs impassivity

emotionlessness and impassivity both are nouns.

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

As nouns, emotionlessness and impassivity are synonyms defined as:

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

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

emotionlessness (noun)	impassivity (noun)
absence of emotion	apathy demonstrated by an absence of emotional reactions
apathy demonstrated by an absence of emotional reactions