n.

1. 樂觀；樂觀主義[U]
   At the airport, he expressed optimism about the talks.

   在機場上，他對談判表示了樂觀。

n.

1. hopefulness and confidence about the future or the success of something.
2. Philosophy  the doctrine, especially as set forth by Leibniz, that this world is the best of all possible worlds.
   ▸the belief that good must ultimately prevail over evil in the universe.