equanimity
noun
Composure and calm in stressful situations; equilibrium
syn. cool, composure, confidence
ant. doubt, excitement, agitation
He reacted with equanimity when he was told that his house was on fire, asking only if the fire department had been called.
When you are being screamed at for no reason, it is difficult to keep your equanimity.
What is Equanimity? ~ Shinzen Young