n.

1. 主意；打算；计划[C][（+of）][+to-v][+that]
   He hit upon the good idea of spending the weekend in the nearby holiday camp.

   他想到一个好主意——去附近度假营过周末。

   He is full of ideas.

   他主意很多。

2. 构想；概念[C][U][（+of）]
   Have you any idea of what he is up to?

   你知道他想干什么吗？

3. 了解，明白[C][（+of）][+wh-]
   I have no idea what to do.

   我不知道该怎么办。

   Jimmie had but a vague idea of world conditions now.

   吉米对当今世界情况只有一点模糊的了解。

4. 臆测；推量[C][+（that）]
   I've an idea that he'll soon quit the job.

   我猜想他不久就要辞掉这工作。

5. 意见，见解；信念[（+about/on）][+that]
   That at least is my idea about friendship.

   至少那是我对友谊的理解。

6. 思想；观念[C][U]
   He destroyed feudal ideas in literature.

   他摧毁了文学中的封建思想。

n.

1. a thought or suggestion as to a possible course of action.
   ▸a mental impression.
   ▸a belief.
2. (the idea) the aim or purpose of an action.
3. Philosophy  (in Platonic thought) an eternally existing pattern of which individual things in any class are imperfect copies.
   ▸(in Kantian thought) a concept of pure reason, not empirically based in experience.