- Noun. A naval officer of the highest rank; the commander of a country's naval forces.
- Noun. A naval officer of high rank, immediately below Admiral of the Fleet; the commander of a fleet or squadron.
- Noun. A flag officer in the United States Navy or Coast Guard of a grade superior to vice admiral and junior to admiral of the fleet (when that grade is used). An admiral is equal in grade or rank to a four star general.
- Noun. The ship which carries the admiral, the flagship; also, the most considerable ship of a fleet.
- Noun. (obsolete) A prince or Saracen leader under the Sultan.
- Noun. (zoological) Any of various nymphalid butterflies of Europe and America, especially a red admiral or white admiral.