The Collaborative International Dictionary of English v.0.48:
Watercourse \Wa"ter*course`\, n. (Shipbuilding) One of the holes in floor or other plates to permit water to flow through. [Webster 1913 Suppl.]WordNet (r) 3.0 (2006):
watercourse n 1: natural or artificial channel through which water flows 2: a natural body of running water flowing on or under the earth [syn: stream, watercourse] 3: a conduit through which water flows [syn: watercourse, waterway]