Impassivity is a related term of tranquility.
As nouns the difference between impassivity and tranquility
is that impassivity is the state of being impassive while tranquility is .
impassivity
English
Noun
(-)
the state of being impassive
tranquility
English
Noun
(en-noun)
Usage notes
* More common spelling in the US; less common in the UK.