1. The commander in chief of a fleet.
2. A flag officer.
3. a. Abbr. ADM or Adm. A commissioned rank in the U.S. Navy or Coast Guard that is above vice admiral and below Admiral of the Fleet. b. One who holds the rank of admiral, Admiral of the Fleet, rear admiral, or vice admiral.
4. Any of various brightly colored butterflies of the genera Limenitis and Vanessa.
5. Archaic The ship carrying an admiral; flagship