NOUN (3)

1. a cavalry unit consisting of two or more troops and headquarters and supporting arms;

2. an air force unit larger than a flight and smaller than a group;

3. a naval unit that is detached from the fleet for a particular task;

The Collaborative International Dictionary of English v.0.48:

Squadron \Squad"ron\ (skw[o^]d"r[u^]n), n. [F. escadron,
   formerly also esquadron, Sp. escuadron, or It. squadrone. See
   Squad.]
   1. Primarily, a square; hence, a square body of troops; a
      body of troops drawn up in a square. [R.]
      [1913 Webster]

            Those half-rounding quards
            Just met, and, closing, stood in squadron joined.
                                                  --Milton.
      [1913 Webster]

   2. (Mil.) A body of cavalry comprising two companies or
      troops, and averaging from one hundred and twenty to two
      hundred men.
      [1913 Webster]

   3. (Naut.) A detachment of vessels employed on any particular
      service or station, under the command of the senior
      officer; as, the North Atlantic Squadron. --Totten.
      [1913 Webster]

   Flying squadron, a squadron of observation or practice,
      that cruises rapidly about from place to place. --Ham.
                                                  Nav. Encyc.
      [1913 Webster]

WordNet (r) 3.0 (2006):

squadron
    n 1: a cavalry unit consisting of two or more troops and
         headquarters and supporting arms
    2: an air force unit larger than a flight and smaller than a
       group
    3: a naval unit that is detached from the fleet for a particular
       task

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "squadron":
   KP, Naval Construction Battalion, RN, Royal Navy, Seabees, USN,
   United States Navy, air arm, air corps, air force, air service,
   argosy, armada, army, army group, battalion, battery, battle group,
   brigade, cadre, coast guard, cohort, column, combat command,
   combat team, company, corps, detachment, detail, division,
   escadrille, field army, field train, file, fleet, flight, flotilla,
   flying column, garrison, kitchen police, legion, maniple, marine,
   merchant fleet, merchant marine, merchant navy, mosquito fleet,
   naval forces, naval militia, naval reserve, navy, organization,
   outfit, phalanx, platoon, posse, rank, regiment, section, squad,
   strategic air force, tactical air force, tactical unit, task force,
   task group, train, troop, unit, wing