1. Not navigable.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• ynnavigable,
• hnnavigable,
• jnnavigable,
• innavigable,
• 8nnavigable,
• 7nnavigable,
• ubnavigable,
• umnavigable,
• ujnavigable,
• uhnavigable,
• unbavigable,
• unmavigable,
• unjavigable,
• unhavigable,
• unnzvigable,
• unnsvigable,
• unnwvigable,
• unnqvigable,
• unnacigable,
• unxaminable

• unpassable.

The adjective form of the word "unnavigable" is "unnavigable" itself.

The plural form of the word "unnavigable" is "unnavigables".

The singular form of the word "unnavigable" is "unnavigable". This word is already in its singular form.