1. To flow or move out of something, as of a liquid. Because the stopper had come loose, most of the water had drained out of the tub by the time I came back for my bath.
2. To cause a liquid to flow or move out of something. In this usage, a noun or pronoun can be used between "drain" and "out." Can you drain the water out? I don't want the pasta to get soggy.
3. To cause something to be emptied of a fluid. In this usage, a noun or pronoun can be used between "drain" and "out." You'll want to drain these tubs out before you try to move them.
to flow out or empty. All the milk drained out of the container onto the bottom of the refrigerator. All the oil drained out of the crankcase.