名詞 optimism:

1. the optimistic feeling that all is going to turn out well
2. a general disposition to expect the best in all things

1. Her mood varied from optimism to extreme depression.
   她的情緒由樂(lè)觀一變而為極度消沉。
2. He swings from wild optimism to total despair.
   他由極其樂(lè)觀一變而為完全絕望。
3. At the outset of her career she was full of optimism but not now.
   她事業(yè)伊始十分樂(lè)觀，但現(xiàn)在已今非昔比了。
4. They professed optimism about the outcome.
   他們對(duì)結(jié)果表示樂(lè)觀。
5. I would caution against undue optimism.
   我奉勸不要過(guò)於樂(lè)觀。
6. Pessimism, when you get used to it, is just as agreeable as optimism.
   悲觀主義者，當(dāng)你習(xí)慣它之后，就和樂(lè)觀主義者一樣令人愜意了。

op.ti.mism

n.（名詞）
A tendency to expect the best possible outcome or dwell on the most hopeful aspects of a situation:
樂(lè)觀主義，樂(lè)觀：期待一切都朝著好的方向發(fā)展或總是考慮事情最有利的方面的一種傾向：
例句：
.There is a touch of optimism in every worry about one`s own moral cleanliness.(Victoria Ocampo)
.在對(duì)自身道德純凈度的每次焦慮中，都存在一種樂(lè)觀因素.(維多利亞·奧卡姆波)

Philosophy
【哲學(xué)】
The doctrine, asserted by Leibnitz, that this world is the best of all possible worlds.
盡善盡美論：由萊布尼茲創(chuàng)建的一種理論，認(rèn)為這個(gè)世界是盡善盡美的
The belief that the universe is improving and that good will ultimately triumph over evil.
樂(lè)觀論：認(rèn)為世界是不斷發(fā)展完善的，善最終必戰(zhàn)勝惡的理論

來(lái)源：
French optimisme
法語(yǔ) optimisme
from New Latin optimum [the greatest good] * see optimum
源自 現(xiàn)代拉丁語(yǔ) optimum [最有利的一面] *參見(jiàn) optimum