1. 马戏团
    A circus is a group that consists of clowns, acrobats, and animals which travels around to different places and performs shows.

circus

    e.g. My real ambition was to work in a circus.
           我的真正理想是在马戏团工作。
    e.g. ...circus performers.
           马戏团演员

2. 闹哄哄的人群;架势很大的活动
    If you describe a group of people or an event as a circus, you disapprove of them because they attract a lot of attention but do not achieve anything useful.

    e.g. It could well turn into some kind of a media circus.
           这很可能会演变成媒体的一场闹剧。
    e.g. ...the travelling circus of political journalists.
           四处奔走的一群政治记者

3. (有时用于街道名称)环形路，环形广场，环形交叉口
    Circus is sometimes used as part of the name of a street which goes in a circle.

    e.g. ...Piccadilly Circus.
           皮卡迪利广场