1. （使）翻转；（使）倾覆；（使）倒下
    If something overturns or if you overturn it, it turns upside down or on its side.

    e.g. The lorry veered out of control, overturned and smashed into a wall...
           卡车突然失控，翻倒撞上了一堵墙。
    e.g. Alex jumped up so violently that he overturned his glass of sherry...
           亚历克斯一下子暴跳起来，结果把他那杯雪利酒都打翻了。

2. 推翻，撤销（判决）
    If someone in authority overturns a legal decision, they officially decide that that decision is incorrect or not valid.

    e.g. When the Russian parliament overturned his decision, he backed down...
           俄罗斯议会推翻了他的决定，他只好作罢。
    e.g. His nine-month sentence was overturned by Appeal Court judge Lord Justice Watkins.
           上诉法院法官沃特金斯撤销了对他作出的9个月徒刑的判决。

3. 颠覆，破坏（政府或体系）
    To overturn a government or system means to remove it or destroy it.

    e.g. He accused his opponents of wanting to overturn the government.
           他指责反对派企图颠覆政府。
    e.g. ...a society where all the old values had been overturned.
           摒弃了所有旧价值观的社会