nonchalance

nonchalancenoun
Translations
His nonchalance about the situation was surprising.
Его безразличие к ситуации было удивительным.
She carried herself with an air of nonchalance.
Она держалась с налётом небрежности.
Definitions
The state of being calm and relaxed, not displaying anxiety, interest, or enthusiasm.
Her nonchalance in the face of danger was both impressive and unsettling.