Innavigable
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
As applied to streams, not capable of or suitable for navigation; impassable by ships or vessels. As applied to vessels in the law of marine insurance, it means unfit for navigation ; so damaged by misadventures at sea as to be no longer capable of making a voyage.
See 3 Kent, Comm. 323, note.