1. 密谋;阴谋
    Conspiracy is the secret planning by a group of people to do something illegal.

    e.g. Seven men, all from Bristol, admitted conspiracy to commit arson...
           7个人都来自布里斯托尔，他们承认了合谋纵火。
    e.g. He believes there probably was a conspiracy to kill President Kennedy in 1963.
           他认为1963年肯尼迪总统遇刺身亡可能是一个阴谋。

2. 阴谋
    A conspiracy is an agreement between a group of people which other people think is wrong or is likely to be harmful.

conspiracy在线翻译

    e.g. It's all part of a conspiracy to dispense with the town centre all together and move everything out to Meadowhall...
           彻底抛开市中心而把所有东西都搬到梅多霍尔购物中心，这完全是一场阴谋的一部分。
    e.g. There was no evidence to link the brigade to any conspiracy against Mr Bush.
           没有证据表明这帮人对布什先生图谋不轨。

3. （为了私利）保持缄默的密约
    If there is a conspiracy of silence about something, people who know about it have agreed that they will not talk publicly about it, although it would probably be a good thing if people in general knew about it.

conspiracy

    e.g. Detectives have run into a conspiracy of silence in the tight-knit communities of the peninsula.
           侦探们犯了难，半岛上各个群体抱成一团，达成了保持缄默的密约。