impassiveness

As an adjective apathetic

is void of feeling; not susceptible of deep emotion; passionless; indifferent.

As a noun impassiveness is

the state of being impassive.

As nouns the difference between impassiveness and openness

is that impassiveness is the state of being impassive while openness is accommodating attitude or opinion, as in receptivity to new ideas, behaviors, cultures, peoples, environments, experiences, etc, different from the familiar, conventional, traditional, or one's own.

Torpor is a related term of impassiveness.

As nouns the difference between torpor and impassiveness

is that torpor is being inactive or stuporous while impassiveness is the state of being impassive.

Numbness is a related term of impassiveness.

As nouns the difference between numbness and impassiveness

is that numbness is absent or reduced sensitivity to cutaneous stimulation while impassiveness is the state of being impassive.

Dullness is a related term of impassiveness.

As nouns the difference between dullness and impassiveness

is that dullness is the quality of being slow to understand things while impassiveness is the state of being impassive.

Insensibility is a synonym of impassiveness.

As nouns the difference between insensibility and impassiveness

is that insensibility is the property of being insensible while impassiveness is the state of being impassive.

Stupidity is a related term of impassiveness.

As nouns the difference between stupidity and impassiveness

is that stupidity is (uncountable) the property of being stupid while impassiveness is the state of being impassive.

Apathy is a related term of impassiveness.

As nouns the difference between apathy and impassiveness

is that apathy is complete lack of emotion or motivation about a person, activity, or object; depression; lack of interest or enthusiasm; disinterest while impassiveness is the state of being impassive.

As nouns the difference between impassiveness and indifference

is that impassiveness is the state of being impassive while indifference is the state of being indifferent.