I
n.
1) to clean out, clear, unblock, unclog a drain
2) to block, clog a drain
3) (misc.) a brain drain
II
v.
1) (d; intr.) to drain from (the blood drained from his face when he heard the news)
2) (D; tr.) to drain of (drain the tank of all water)
3) (N; used with an adjective) they drained the swamps dry