noun.
The quality of being calm and even-tempered; composure.
The Century Dictionary and Cyclopedia
noun.
Evenness of mind or temper; calmness or firmness, especially under conditions adapted to excite great emotion; a state of resistance to elation, depression, anger, etc.
the GNU version of the Collaborative International Dictionary of English
noun.
Evenness of mind; that calm temper or firmness of mind which is not easily elated or depressed; patience; calmness; composure.
noun.
The state of being calm, stable and composed, especially under stress.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
steadiness of mind under stress
Word Usage
"We weren’t rolling in money, but we certainly had enough to live well, and I approached my thirties with a certain … no, I really don’t want to use the word equanimity here, even though it’s apt."