Admiral is one of the highest ranks in some navies, and in many navies is the highest rank. In the Commonwealth nations and the United States, a "full" admiral is equivalent to a "full" general in the army, and is above vice admiral and below admiral of the fleet, or fleet admiral. In NATO, admirals have a rank code of OF-9 as a four-star rank.
The word admiral in Middle English comes from Anglo-French amiral, "commander", from Medieval Latin admiralis, admirallus. These themselves come from Arabic am?r, or am?r al- (? ), "commander of", as in am?r al-ba?r (? ), "commander of the sea". The term was in use for the Greco-Arab naval leaders of Norman Sicily, which had formerly been ruled by Arabs, at least by the early 11th century.
The Norman Roger II of Sicily (1095-1154), employed a Greek Christian known as George of Antioch, who previously had served as a naval commander for several North African Muslim rulers. Roger styled George in Abbasid fashion as Amir of Amirs, i.e. "Commander of Commanders", with the title becoming Latinized in the 13th century as ammiratus ammiratorum.
The Sicilians and later Genoese took the first two parts of the term and used them as one word, amiral, from their Aragon opponents. The French and Spanish gave their sea commanders similar titles while in Portuguese the word changed to almirante. As the word was used by people speaking Latin or Latin-based languages it gained the "d" and endured a series of different endings and spellings leading to the English spelling admyrall in the 14th century and to admiral by the 16th century.
The word "admiral" has come to be almost exclusively associated with the highest naval rank in most of the world's navies, equivalent to the army rank of general. However, this was not always the case; for example, in some European countries prior to the end of World War II, admiral was the third highest naval rank after general admiral and grand admiral.
The rank of admiral has also been subdivided into various grades, several of which are historically extinct while others remain in use in most present day navies. The Royal Navy used the colours red, white, and blue, in descending order to indicate seniority of its admirals until 1864; for example, Horatio Nelson's highest rank was vice admiral of the white. The generic term for these naval equivalents of army generals is flag officer. Some navies have also used army-type titles for them, such as the Cromwellian "general at sea".
The rank insignia for an admiral often involves four stars or similar devices, or three stripes over a broad stripe, but there are many cases where the insignia do not involve four stars or similar devices.
Royal Australian Navy
Royal Brunei Navy
Royal Cambodian Navy
Imperial Iranian Navy
Islamic Republic of Iran Navy
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Kuwait Naval Force
Royal Malaysian Navy
Royal Norwegian Navy
Royal Navy of Oman
Imperial Russian Navy (1884--1904)
Russian Navy pre 2010
Russian Navy post 2010
Russian Navy (sleeve)
Fariq awwal (? )
Ukrainian Navy (old version)
Ukrainian Navy (new version)
Ukrainian Navy (sleeve)
Republic of Vietnam Navy (1955-1963)
Republic of Vietnam Navy (1964-1975)
Post-World War II rank is Bakurocho taru kaish? or Kaish? serve as Chief of Staff, Joint Staff with limited function as an advisory staff to Minister of Defense (Japan), compared to Kaigun-taish? (Imperial Japanese Navy) during 1872-1873 and 1898-1945.