Source : Webster's Revised Unabridged Dictionary (1913)

Besiege \Be*siege"\, v. t. [imp. & p. p. {Besieged}; p. pr. &
   vb. n. {Besieging}.] [OE. bisegen; pref. be- + segen to
   siege. See {Siege}.]
   To beset or surround with armed forces, for the purpose of
   compelling to surrender; to lay siege to; to beleaguer; to
   beset.

         Till Paris was besieged, famished, and lost. --Shak.

   Syn: To environ; hem in; invest; encompass.

Besieging \Be*sie"ging\, a.
   That besieges; laying siege to. -- {Be*sie"ging*ly}, adv.

Source : WordNet®

besieging
     n : the action of an armed force that surrounds a fortified
         place and isolates it while continuing to attack [syn: {siege},
          {beleaguering}, {military blockade}]