noun
(countable) A country's entire maritime military force, including ships and personnel.
(countable) A governmental department in charge of a country's maritime military force.
(archaic, countable) Any fleet of maritime vessels, and especially the entire fleet of any particular nationality, including vessels that are commercial, military, or both.
(countable and uncountable) A dark blue colour, usually called navy blue.
adjective
Having the dark blue colour of navy blue.
(military) Belonging to the navy; typical of the navy.