besieging

from WordNet (r) 3.0 (2006)

besieging
    n 1: the action of an armed force that surrounds a fortified
         place and isolates it while continuing to attack [syn:
         {siege}, {besieging}, {beleaguering}, {military blockade}]

from The Collaborative International Dictionary of English v.0.48

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.
   [1913 Webster]

         Till Paris was besieged, famished, and lost. --Shak.
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   Syn: To environ; hem in; invest; encompass.
        [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Besieging \Be*sie"ging\, a.
   That besieges; laying siege to. -- {Be*sie"ging*ly}, adv.
   [1913 Webster]