a substance or object that absorbs heat

At the back is a massive wall that acts as a heat sink - it cools the house in summer and in winter acts like a big radiator. 后面是一堵巨大的墙，作为热汇——在夏天为房子降温，在冬天则像一个大散热器。

A one-degree temperature increase would lower the effectiveness of lakes designed to be heat sinks for power plants. 温度升高一度，设计用作发电厂散热器的湖泊的效率就会降低。

a device in a computer, mobile phone, etc. that absorbs heat so that important parts do not get too hot and stop working

The processor has its own heat sink and usually a fan, too. 处理器有自己的散热器，通常还有一个风扇。