n.

1. 乐观主义[U]
   At the airport, he expressed optimism about the talks.

   在机场上，他对谈判表示了乐观。

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.