The Collaborative International Dictionary of English v.0.48:

Nomenclator \No"men*cla`tor\, n. [L., fr. nomen name + calare to
   call. See Name, and Calendar.]
   1. One who calls persons or things by their names.
      [1913 Webster]

   Note: In Rome, candidates for office were attended each by a
         nomenclator, who informed the candidate of the names of
         the persons whom they met and whose votes it was
         desirable to solicit.
         [1913 Webster]

   2. One who gives names to things, or who settles and adjusts
      the nomenclature of any art or science; also, a list or
      vocabulary of technical names.
      [1913 Webster]