The Collaborative International Dictionary of English v.0.48:

Cruet \Cru"et\ (kr[udd]"[e^]t), n. [Anglo-French cruet, a dim.
   from OF. crue, cruie; of German or Celtic origin, and akin to
   E. crock an earthen vessel.]
   1. A bottle or vessel; esp., a vial or small glass bottle for
      holding vinegar, oil, pepper, or the like, for the table;
      a caster. --Swift.
      [1913 Webster]

   2. (Eccl.) A vessel used to hold wine, oil, or water for the
      service of the altar.
      [1913 Webster] cruet-stand

WordNet (r) 3.0 (2006):

cruet
    n 1: bottle that holds wine or oil or vinegar for the table
         [syn: cruet, crewet]