magnanimity (n.)

mid-14c., "loftiness of thought or purpose, greatness of mind or heart, habit of feeling and acting worthily under all circumstances," from Old French magnanimité "high-mindedness, generosity of spirit," from Latin magnanimitatem (nominative magnanimitas) "greatness of soul, high-mindedness," from magnanimus "having a great soul," from magnus "great" (from PIE root *meg- "great") + animus "mind, soul, spirit" (see animus).

Probably a loan-translation of Greek megalopsykhos "high-souled, generous" (Aristotle) or megathymus "great-hearted." The narrower sense of "superiority to petty resentments or jealousies, generous disregard of injuries" (by 1771).