Equanimity

Charles Buck Theological Dictionary

Is an even, uniform state of mind, amidst all the vicissitudes of time and changes of circumstances to which we are subject in the present state. One of this disposition is not dejected when under adversity, nor elated when in the height of prosperity: he is equally affable to others, and contented in himself. The excellency of this disposition is beyond all praise. It may be considered as the grand remedy for all the diseases and miseries of life, and the only way by which we can preserve the dignity of our characters as men and as Christians.

Webster's Dictionary

(n.) Evenness of mind; that calm temper or firmness of mind which is not easily elated or depressed; patience; calmness; composure; as, to bear misfortunes with equanimity.