乐观主义（另称乐天派）是指一种对一切事物采与正面看法的观念。是悲观主义的相反词。乐观的人不会想到一件事的缺点与瑕疵，永远以正面的想法对待身边的一切。

Optimism is a mental attitude or world view. A common idiom used to illustrate optimism versus pessimism is a glass with water at the halfway point, where the optimist is said to see the glass as half full and the pessimist sees the glass as half empty.