The Collaborative International Dictionary of English v.0.48:

Sanctus \Sanc"tus\, n. [L. sanctus, p. p. of sancire.]
   1. (Eccl.) A part of the Mass, or, in Protestant churches, a
      part of the communion service, of which the first words in
      Latin are Sanctus, sanctus, sanctus [Holy, holy, holy]; --
      called also Tersanctus.
      [1913 Webster]

   2. (Mus.) An anthem composed for these words.
      [1913 Webster]

   Sanctus bell, a small bell usually suspended in a bell cot
      at the apex of the nave roof, over the chancel arch, in
      mediaeval churches, but a hand bell is now often used; --
      so called because rung at the singing of the sanctus, at
      the conclusion of the ordinary of the Mass, and again at
      the elevation of the host. Called also Mass bell,
      sacring bell, saints' bell, sance-bell, sancte
      bell.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "Sanctus":
   Agnus Dei, Alleluia, Anamnesis, Blessing, Canon, Collect,
   Communion, Consecration, Credo, Dismissal, Epistle, Fraction,
   Gloria, Gospel, Gradual, Introit, Kyrie, Kyrie Eleison,
   Last Gospel, Lavabo, Offertory, Paternoster, Pax, Post-Communion,
   Preface, Secreta, Tersanctus, Tract