Equanimity
Part of speech: noun
Definition: The state of being calm, stable and composed, especially under stress.
Example sentence: A son can bear with equanimity the loss of his father, but the loss of his inheritance may drive him to despair.
Calmness
Part of speech: noun
Definition: The state of being calm; tranquillity; silence.The product of being calm.
Example sentence: There are no better cosmetics than a severe temperance and purity, modesty and humility, a gracious temper and calmness of spirit; and there is no true beauty without the signatures of these graces in the very countenance.