calmness and composure, especially in a difficult situation. "she accepted both the good and the bad with equanimity"
Equanimity (Latin: æquanimitas, having an even mind) is a state of psychological stability and composure which is undisturbed by experience of or exposure to emotions, pain, or other phenomena that may cause others to lose the balance of their mind.
Neither a thought nor an emotion, it is rather the steady conscious realization of reality's transience. It is the ground for wisdom and freedom and the protector of compassion and love. While some may think of equanimity as dry neutrality or cool aloofness, mature equanimity produces a radiance and warmth of being. The Buddha described a mind filled with equanimity as "abundant, exalted, immeasurable, without hostility and without ill-will."
Krishna tells Arjuna that all feelings are transitory and fleeting and that the wise are not tormented by these feelings
"Perform your duty equipoised, O Arjuna, abandoning all attachment to success or failure. Such equanimity is called yoga." – Bhagavad Gita (II.48)
"He is a perfect yogi who, by comparison to his own self, sees the true equality of all beings, in both, their happiness and their distress, O Arjuna." - Bhagavad Gita (VI.32)
Another Sanskrit term for equanimity is upekṣhā. This is the term used by Patanjali in his Yoga Sutras (1.33) Here upekṣhā is considered to be one of the four sublime attitudes, along with loving-kindness (maitri), compassion (karuṇā), and joy (mudita).