The Collaborative International Dictionary of English v.0.48:

Registrar \Reg"is*trar\ (-tr?r), n. [LL. registrarius, or F.
   r['e]gistraire. See Register.]
   One who registers; a recorder; a keeper of records; as, a
   registrar of births, deaths, and marriages. See Register,
   n., 3.
   [1913 Webster]

WordNet (r) 3.0 (2006):

registrar
    n 1: a person employed to keep a record of the owners of stocks
         and bonds issued by the company
    2: the administrator responsible for student records
    3: someone responsible for keeping records [syn: registrar,
       record-keeper, recorder]