The Collaborative International Dictionary of English v.0.48:
drainboard \drain"board`\ n. a board beside a kitchen sink having a surface inclined so as to drain into the sink. Syn: draining board. [WordNet 1.5]WordNet (r) 3.0 (2006):
drainboard n 1: a board beside a kitchen sink and inclined to drain into the sink [syn: drainboard, draining board]