WATERWAY
watercourse, waterway
(noun) a conduit through which water flows
waterway
(noun) a navigable body of water
Source: WordNet® 3.1
Etymology
Noun
waterway (plural waterways)
A body of water, such as a river, channel or canal, that is navigable.
A conduit or watercourse, such as on the deck of a ship, to drain water.
Source: Wiktionary
Wa"ter*way`, n. (Naut.)
Definition: Heavy plank or timber extending fore and aft the whole length
of a vessel's deck at the line of junction with the sides, forming a
channel to the scuppers, which are cut through it. In iron vessels
the waterway is variously constructed.
Source: Webster’s Unabridged Dictionary 1913 Edition