The Collaborative International Dictionary of English v.0.48:

Surround \Sur*round"\, v. t. [imp. & p. p. Surrounded; p. pr.
   & vb. n. Surrounding.] [OF. suronder to overflow, LL.
   superundare; fr. L. super over + undare to rise in waves,
   overflow, fr. unda wave. The English sense is due to the
   influence of E. round. See Super-, and Undulate, and cf.
   Abound.]
   1. To inclose on all sides; to encompass; to environ.
      [1913 Webster]

   2. To lie or be on all sides of; to encircle; as, a wall
      surrounds the city.
      [1913 Webster]

            But could instead, and ever-during dark
            Surrounds me.                         --Milton.
      [1913 Webster]

   3. To pass around; to travel about; to circumnavigate; as, to
      surround the world. [Obs.] --Fuller.
      [1913 Webster]

   4. (Mil.) To inclose, as a body of troops, between hostile
      forces, so as to cut off means of communication or
      retreat; to invest, as a city.
      [1913 Webster]

   Syn: To encompass; encircle; environ; invest; hem in; fence
        about.
        [1913 Webster]

WordNet (r) 3.0 (2006):

surrounded
    adj 1: confined on all sides; "a camp surrounded by enemies";
           "the encircled pioneers" [syn: surrounded, encircled]

Moby Thesaurus II by Grady Ward, 1.0:

23 Moby Thesaurus words for "surrounded":
   circumscribed, circumscript, compassed, defined, definite,
   delimited, demarcated, determinate, determined, encircled,
   enclosed, encompassed, enfolded, enveloped, environed, fixed,
   hedged about, lapped, set, specific, stated, wrapped, wreathed