The Collaborative International Dictionary of English v.0.48:

Beleaguer \Be*lea"guer\, v. t. [imp. & p. p. Beleaguered; p.
   pr. & vb. n. Beleaguering.] [D. belegeren (akin to G.
   belagern, Sw. bel[aum]gra, Dan. beleire); pref. be- = E. be-
   + leger bed, camp, army, akin to E. lair. See Lair.]
   To surround with an army so as to preclude escape; to
   besiege; to blockade.
   [1913 Webster]

         The wail of famine in beleaguered towns. --Longfellow.
   [1913 Webster]

   Syn: To block up; environ; invest; encompass.
        [1913 Webster]

WordNet (r) 3.0 (2006):

beleaguer
    v 1: annoy persistently; "The children teased the boy because of
         his stammer" [syn: tease, badger, pester, bug,
         beleaguer]
    2: surround so as to force to give up; "The Turks besieged
       Vienna" [syn: besiege, beleaguer, surround, hem in,
       circumvent]

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "beleaguer":
   annoy, bedevil, beset, besiege, blockade, bound, box in, cage,
   chamber, close in, compass, contain, coop, coop in, coop up,
   cordon, cordon off, corral, encircle, enclose, encompass, enshrine,
   envelop, fence in, gnaw, harass, harry, hedge in, hem in, house in,
   impound, imprison, incarcerate, include, invest, jail, kennel,
   lay siege to, leaguer, mew, mew up, pen, pen in, pester, plague,
   pocket, quarantine, rail in, shrine, shut in, shut up, siege,
   soften up, stable, storm, surround, tease, wall in, wrap, yard,
   yard up