The Collaborative International Dictionary of English v.0.48:

Rabbinist \Rab"bin*ist\ (r[a^]b"b[i^]n*[i^]st), n. [Cf. F.
   rabbiniste.]
   One among the Jews who adhered to the Talmud and the
   traditions of the rabbins, in opposition to the Karaites, who
   rejected the traditions.
   [1913 Webster]