n.1 an inclination to hopefulness and confidence (opp. PESSIMISM).
2 Philos. a the doctrine, esp. as set forth by Leibniz, that this world is the best of all possible worlds. b the theory that good must ultimately prevail over evil in the universe.
Derivatives:
optimist n. optimistic adj. optimistically adv.
Etymology: F optimisme f. L OPTIMUM