The Collaborative International Dictionary of English v.0.48:

Listen \Lis"ten\ (l[i^]s"'n), v. i. [imp. & p. p. Listened
   (l[i^]s"'nd); p. pr. & vb. n. Listening.] [OE. listnen,
   listen, lustnen, lusten, AS. hlystan; akin to hlyst hearing,
   OS. hlust, Icel. hlusta to listen, hlust ear, AS. hlosnian to
   wait in suspense, OHG. hlos[=e]n to listen, Gr. kly`ein, and
   E. loud. [root]41. See Loud, and cf. List to listen.]
   1. To give close attention with the purpose of hearing; to
      give ear; to hearken; to attend.
      [1913 Webster]

            When we have occasion to listen, and give a more
            particular attention to some sound, the tympanum is
            drawn to a more than ordinary tension. --Holder.
      [1913 Webster]

   2. To give heed; to yield to advice; to follow admonition; to
      obey.
      [1913 Webster]

            Listen to me, and by me be ruled.     --Tennyson.
      [1913 Webster]

   To listen after, to take an interest in. [Obs.]
      [1913 Webster]

            Soldiers note forts, armories, and magazines;
            scholars listen after libraries, disputations, and
            professors.                           --Fuller.

   Syn: To attend; hearken. See Attend.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Listen \Lis"ten\, v. t.
   To attend to. [Obs.] --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

listen
    v 1: hear with intention; "Listen to the sound of this cello"
    2: listen and pay attention; "Listen to your father"; "We must
       hear the expert before we make a decision" [syn: listen,
       hear, take heed]
    3: pay close attention to; give heed to; "Heed the advice of the
       old men" [syn: heed, mind, listen]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "listen":
   NB, attend, attend to, auscultate, be all ears, bend an ear, bug,
   cock the ears, eavesdrop, examine by ear, give attention,
   give audience to, give ear, give ear to, hark, hear, hear out,
   hearken, hearken to, heed, intercept, lend an ear, listen at,
   listen in, listen to, mind, obey, pay attention to, sit in on,
   straitened circumstances, tap, wiretap