The Collaborative International Dictionary
Innavigable
Innavigable \In*nav"i*ga*ble\, a. [L. innavigabilis : cf. F.
innavigable. See In- not, and Navigable.]
Incapable of being navigated; impassable by ships or vessels.
--Drygen. -- In*nav"i*ga*bly, adv.
Wiktionary
innavigable
a. Incapable of being navigated; impassable by ships etc.
Usage examples of "innavigable".
Long ago it had been a thing of rapids and waterfalls, ferocious and all but innavigable for hundreds of miles.