WordNet (r) 3.0 (2006):

Holy Sacrament
    n 1: a Christian sacrament commemorating the Last Supper by
         consecrating bread and wine [syn: Holy Eucharist,
         Eucharist, sacrament of the Eucharist, Holy
         Sacrament, Liturgy, Eucharistic liturgy, Lord's
         Supper]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "Holy Sacrament":
   Communion, Eucharist, Holy Communion, Host, Last Supper,
   Sacrament Sunday, altar bread, bread, bread and wine,
   consecrated bread, consecrated elements, consubstantiation,
   elements, impanation, intinction, loaf, real presence, subpanation,
   the Holy Sacrament, the Sacrament, transubstantiation, wafer