1. Incapable of being sailed on or over; not admitting of navigation.
1579–80. North, Plutarch (1595), 1. Deepe drye sands without water, full of foule ill fauoured venimous beasts, or much mudde vnnauigable.
1604. E. G[rimstone], D’Acosta’s Hist. Indies, I. xxii. 72. The sea was made unnavigable, through the aboundance of banckes, rockes.
1616. Healey, Theophrastus, To the Reader. In Winter, the Seas were lockt vp;… vtterly vnnauigable.
1697. Dryden, Æneis, VI. 341. There th’ unnavigable Lake extends.
1719. De Foe, Crusoe, II. (Globe), 595. An unnavigable Ocean, where Ship never sail’d.
1798. S. & Ht. Lee, Canterb. T., II. 440. A river,—wholly unnavigable from its rude course and stony bed.
1836. W. Irving, Astoria, I. 181. The men returned, therefore, in despair, and declared the river unnavigable.
1898. F. T. Bullen, in Nat. Rev., Aug., 856. The unnavigable coast of Palawan.
b. fig. or in fig. context.
1656. Cowley, Pindar. Odes, Praise of P., i. Pindars unnavigable Song Like a swoln Flood from some steep Mountain pours along.
1688. Prior, Ode on Exod. iii. 14, ii. Yet cease to hope thy short-liv’d Bark shall ride Down spreading Fate’s unnavigable Tide.
1693. Dryden, Juvenal, X. 13. Some who the depths of Eloquence have found, In that unnavigable Stream were Drown’d.
1768–74. Tucker, Lt. Nat. (1834), I. 610. Nor would the unnavigable gulph utterly exclude his hopes.
c. Adverse to navigation.
a. 1641. Bp. Mountagu, Acts & Mon. (1642), 253. He puts to Sea … at an unseasonable, and unnavigable time of the yeare.
2. Of a vessel: Incapable of being navigated.
1755. Magens, Insurances, II. 139. When a Ship insured is become unnavigable.
