to draw off (liquid) gradually or completely

of liquid: to flow off gradually or completely

to make or become empty or dry by causing or allowing liquid to drain away

to empty (something) by drawing off liquid

drain the pond

to empty (e.g. a glass) (something) by drinking the contents

He drained his glass

to carry away the surface water of (something)

The river that drains the area

to make (something) gradually dry

drain a swamp

to exhaust (somebody) physically or emotionally

to deplete or empty (something) by gradually using up resources etc

a war that drained the nation of youth and wealth