the ability to form pictures in the mind

My younger son has a very vivid (= active) imagination. 我的小儿子想象力很丰富。

I can never make up stories - I have absolutely no imagination. 我从来都不会编故事——我根本没什么想象力。

For some reason the story captured/caught the imagination of the public (= made them very interested). 由于某种原因，这件事引起了公众的关注。

It couldn't by any stretch of the imagination be described as a (= it is certainly not a) beautiful city. 这座城市再怎么说也称不上漂亮。

There's a sex scene in the film which apparently leaves nothing to the imagination (= shows sexual parts of the body very clearly). 这部电影中有一个十分露骨的性爱场面，没有留下任何想象的余地。

something that you think exists or is true, although in fact it is not real or true

Was she paying him a lot of attention or was it just my imagination? 她是特别注意他呢，还是这一切只是我的臆想？

Is it my imagination or is David behaving strangely at the moment? 是我的错觉呢，还是戴维现在真的是行为古怪？

the ability to think of new ideas

It's a job that needs someone with a bit of imagination. 做这项工作需要有一点儿创造力。