The liquid that stays on top after some stuff has settled at the bottom.
After spinning the mixture fast, the supernatant was taken off carefully.
快速旋轉混合物後,小心地取走了上清液。
The liquid part left after the heavier parts are taken out.
We studied the supernatant to find out how much stuff was in it.
我們研究了上清液,以了解其中有多少物質。