a pipe that carries away dirty water or other liquid waste 下水道；排水管
We had to call in a plumber to unblock the drain.
我们只得叫个管子工来疏通下水道。
The drains (= the system of pipes) date from the beginning of the century.
下水道排水系统是本世纪初修的。
verb
[T, I] ~ (sth)to make sth empty or dry by removing all the liquid from it; to become empty or dry in this way 排空；（使）流光；放干
Drain and rinse the pasta.
把通心粉过一过水。
The marshes have been drained.
沼泽地里的水已排干。
You will need to drain the central heating system before you replace the radiator.
你得先把中央供暖系统的水排净再更换散热器。
The swimming pool drains very slowly.
游泳池里的水排得很慢。
Leave the dishes to drain.
把碟子控干。