The Collaborative International Dictionary of English v.0.48:

Enrollment \En*roll"ment\, n. [Cf. F. enr[^o]lement.] [Written
   also enrolment.]
   1. The act of enrolling; registration. --Holland.
      [1913 Webster]

   2. A writing in which anything is enrolled; a register; a
      record. --Sir J. Davies.
      [1913 Webster]

WordNet (r) 3.0 (2006):

enrollment
    n 1: the act of enrolling [syn: registration, enrollment,
         enrolment]
    2: the body of people (such as students) who register or enroll
       at the same time [syn: registration, enrollment]