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]

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "cruet":
   Agnus Dei, Holy Grail, Host, Pieta, Sanctus bell, Sangraal, ark,
   asperger, asperges, aspergillum, bambino, beadroll, beads,
   calabash, candle, canteen, carafe, carboy, caster, censer, chalice,
   chaplet, chrismal, chrismatory, ciborium, cross, crucifix, cruse,
   decanter, demijohn, eucharistial, ewer, fifth, flacon, flagon,
   flask, flasket, font, gourd, hipflask, holy cross, holy water,
   holy-water font, holy-water sprinkler, hot-water bottle, icon,
   incensory, jar, jeroboam, jug, lota, magnum, matzo, menorah,
   mezuzah, mikvah, monstrance, mussuk, olla, osculatory, ostensorium,
   paschal candle, pax, phial, phylacteries, prayer shawl,
   prayer wheel, pyx, relics, reliquary, rood, rosary, sacramental,
   sacred relics, sacring bell, shofar, stoup, sukkah, tabernacle,
   tallith, thurible, urceole, vacuum bottle, veronica, vial,
   vigil light, votive candle