The Collaborative International Dictionary of English v.0.48:

Enroll \En*roll"\, v. t. [imp. & p. p. Enrolled; p. pr. & vb.
   n. Enrolling.] [Pref. en- + roll: cf. F. enr[^o]ler; pref.
   en- (L. in) + r[^o]le roll or register. See Roll, n.]
   [Written also enrol.]
   1. To insert in a roil; to register or enter in a list or
      catalogue or on rolls of court; hence, to record; to
      insert in records; to leave in writing; as, to enroll men
      for service; to enroll a decree or a law; also,
      reflexively, to enlist.
      [1913 Webster]

            An unwritten law of common right, so engraven in the
            hearts of our ancestors, and by them so constantly
            enjoyed and claimed, as that it needed not
            enrolling.                            --Milton.
      [1913 Webster]

            All the citizen capable of bearing arms enrolled
            themselves.                           --Prescott.
      [1913 Webster]

   2. To envelop; to inwrap; to involve. [Obs.] --Spenser.
      [1913 Webster]

WordNet (r) 3.0 (2006):

enrol
    v 1: register formally as a participant or member; "The party
         recruited many new members" [syn: enroll, inscribe,
         enter, enrol, recruit]