1. 概述；概括
    If you outline an idea or a plan, you explain it in a general way.

outline

    e.g. The mayor outlined his plan to clean up the town's image...
           市长概述了他整顿市容的计划。
    e.g. The methods outlined in this book are only suggestions.
           本书概括的一些方法仅供参考。

2. 概要；梗概
    An outline is a general explanation or description of something.

    e.g. Following is an outline of the survey findings...
           以下是调查结果概要。
    e.g. The proposals were given in outline by the Secretary of State.
           国务卿对提议进行了简要的概述。

3. （因背后的光线）显示…的轮廓（或外形）
    You say that an object is outlined when you can see its general shape because there is light behind it.

    e.g. The Ritz was outlined against the lights up there...
           高悬的灯光映照出里兹饭店的轮廓。
    e.g. It was a beautiful sight outlined above the starry sky.
           星空之上映衬出美景。

4. （尤指模糊的）轮廓，外形
    The outline of something is its general shape, especially when it cannot be clearly seen.

outline

    e.g. He could see only the hazy outline of the goalposts.
           他只能看见球门柱模糊的轮廓。