The Collaborative International Dictionary of English v.0.48:

Surgeon \Sur"geon\, n. [OE. surgien, OF. surgien, contr. fr.
   chirurgien. See Chirurgeon.]
   1. One whose profession or occupation is to cure diseases or
      injuries of the body by manual operation; one whose
      occupation is to cure local injuries or disorders (such as
      wounds, dislocations, tumors, etc.), whether by manual
      operation, or by medication and constitutional treatment.
      [1913 Webster]

   2. (Zool.) Any one of numerous species of chaetodont fishes
      of the family Teuthidae, or Acanthuridae, which have
      one or two sharp lancelike spines on each side of the base
      of the tail. Called also surgeon fish, doctor fish,
      lancet fish, and sea surgeon.
      [1913 Webster]

   Surgeon apothecary, one who unites the practice of surgery
      with that of the apothecary. --Dunglison.

   Surgeon dentist, a dental surgeon; a dentist.

   Surgeon fish. See def. 2, above.

   Surgeon general.
      (a) In the United States army, the chief of the medical
          department.
      (b) In the British army, a surgeon ranking next below the
          chief of the medical department.
          [1913 Webster]

WordNet (r) 3.0 (2006):

Surgeon General
    n 1: the head of the United States Public Health Service
    2: the senior medical officer in an Army or Navy