Nav·i·ga·ble a. Capable of being navigated; deep enough and wide enough to afford passage to vessels; as, a navigable river.
Note: ☞ By the common law, a river is considered as navigable only so far as the tide ebbs and flows in it. This is also the doctrine in several of the United States. In other States, the doctrine of the civil law prevails, which is, that a navigable river is a river capable of being navigated, in the common sense of the term.
-- Nav*i*ga*ble*ness, n. -- Nav*i*ga*bly, adv.
adj : able to be sailed on or through safely; "navigable waters";
"a navigable channel"