Source : Webster's Revised Unabridged Dictionary (1913)

Fort \Fort\, n. [F., from fort strong, L. fortis; perh. akin to
   Skr. darh to fix, make firm, and to E. firm Cf. {Forte},
   {Force}, {Fortalice}, {Comfort}, {Effort}.] (Mil.)
   A strong or fortified place; usually, a small fortified
   place, occupied only by troops, surrounded with a ditch,
   rampart, and parapet, or with palisades, stockades, or other
   means of defense; a fortification.

         Detached works, depending solely on their own strength,
         belong to the class of works termed forts. --Farrow.

Source : WordNet®

fort
     n 1: a fortified military post where troops are stationed [syn: {garrison}]
     2: a fortified defensive structure [syn: {fortress}]

fort
     v 1: gather in, or as if in, a fort, as for protection or defense
          [syn: {fort up}]
     2: enclose by or as if by a fortification [syn: {fortify}]
     3: station (troops) in a fort