The Collaborative International Dictionary of English v.0.48:

Fleet \Fleet\, n. [OE. flete, fleote, AS. fle['o]t ship, fr.
   fle['o]tan to float, swim. See Fleet, v. i. and cf.
   Float.]
   A number of vessels in company, especially war vessels; also,
   the collective naval force of a country, etc.
   [1913 Webster]

   Fleet captain, the senior aid of the admiral of a fleet,
      when a captain. --Ham. Nav. Encyc.
      [1913 Webster]