noun

• (military, now informal) The commander of a naval squadron or fleet, regardless of formal rank.
• (military) The appointed commander of a navy, regardless of formal title.
• (military) A high rank in the British and American Navies, NATO grade OF-9, equivalent ranks in other navies, in coast guards, etc.
  "... from my experience in Ours as well as from my former intimacy with many Officers of Note in the British Navy, I am convinced that the Parity of Rank between Sea & land or Marine Officers, is of more consequence to the harmony of the Service, than hath generally been imagined. — in the British Establishment — an Admiral ranks with a Genl a Vice Admiral with a Lieut Genl a Rear Admiral with a Major Genl a Commodore with a Brigadier Genl — a Captain with a Colonel, a master & Commander with a Lieut Colnel — a Lieut. Commanding with a Major, and a Lieutenant in the Navy Ranks with a Captain of Horse, Foot or Marines. — I propose not our Enemies as an Example for our Genl imitation — Yet as their Navy is the best regulated of any in the World, we must in Some degree imitate them and Aim at such further improvement as may one day make ours Vie with and Exceed theirs."
• (zoology) Any of several species of nymphalid butterflies of the genera Kaniska, Limenitis and Vanessa.