(n.) The possession of one's powers; calmness; self-command; presence of mind; composure.

aplomb assurance ataraxy balance calmness composure confidence constraint control coolness discipline equability equanimity equilibrium imperturbability independence level head levelheadedness phlegm poise possession presence of mind restraint sangfroid self-assurance self-command self-confidence self-conquest self-control self-denial self-discipline self-government self-mastery self-restraint well-regulated mind