waterway

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A navigable body of water, such as a river, channel, or canal.
• noun A channel at the edge of a ship's deck to drain away water.

from The Century Dictionary.

• noun A channel or passage of water; a water-route; specifically, that part of a river, arm of the sea, or the like through which vessels enter or depart; the fairway.
• noun In ship-building, a name given to the thick planks at the outside of the deck, worked over the ends of the beams, and fitting against the inside of the top-timbers, to which, as well as to the ends of the beams, they are bolted, thus forming an important binding.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Naut.) 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.
• Same as water course.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A body of water, such as a river, channel or canal, that can be navigated by boats or ships.
• noun A conduit or watercourse, such as on the deck of a ship, to drain water.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a navigable body of water
• noun a conduit through which water flows