The Collaborative International Dictionary of English v.0.48:

Matriculation \Ma*tric`u*la"tion\, n.
   The act or process of matriculating; the state of being
   matriculated.
   [1913 Webster]

WordNet (r) 3.0 (2006):

matriculation
    n 1: admission to a group (especially a college or university)
         [syn: matriculation, matric]