The Collaborative International Dictionary of English v.0.48:

Eucharist \Eu"cha*rist\, n. [L. eucharistia, Gr. e'ycharisti`a,
   lit., a giving of thanks; e'y^ + cha`ris favor, grace,
   thanks; akin to chai`rein to rejoice, and prob. to yearn: cf.
   F. eucharistie.]
   1. The act of giving thanks; thanksgiving. [Obs.]
      [1913 Webster]

            Led through the vale of tears to the region of
            eucharist and hallelujahs.            --South.
      [1913 Webster]

   2. (Eccl.) The sacrament of the Lord's Supper; the solemn act
      of ceremony of commemorating the death of Christ, in the
      use of bread and wine, as the appointed emblems; the
      communion. -- See Sacrament. Eucharistic

WordNet (r) 3.0 (2006):

Eucharist
    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:

29 Moby Thesaurus words for "Eucharist":
   Communion, Holy Communion, Host, Last Supper, Sacrament Sunday,
   altar bread, baptism, bread, bread and wine, confirmation,
   consecrated bread, consecrated elements, consubstantiation,
   elements, extreme unction, holy orders, impanation, intinction,
   loaf, matrimony, penance, real presence, seven sacraments,
   subpanation, the Eucharist, the Holy Sacrament, the Sacrament,
   transubstantiation, wafer



The Devil's Dictionary (1881-1906):

EUCHARIST, n.  A sacred feast of the religious sect of Theophagi.
    A dispute once unhappily arose among the members of this sect as
to what it was that they ate.  In this controversy some five hundred
thousand have already been slain, and the question is still unsettled.