Definition: not easily ruffled, disturbed, or prejudiced <especially under stress>; composed; having a balanced or mild disposition; calm
     See also: Stress Hardy

Derivation: Latin, “with even mind”

• A compassionate heart still feels anger, greed, jealousy, and other such emotions. But it accepts them for what they are with equanimity, and cultivates the strength of mind to let them arise and pass without identifying with or acting upon them. — Stephen Batchelor (1953-) Scottish Buddhist philosopher
• Even a happy life cannot be without a measure of darkness, and the word happy would lose its meaning if it were not balanced by sadness. It is far better to take things as they come along with patience and equanimity. — Carl Gustav Jung (1875-1961) Swiss psychiatrist