The word Mass is the general designation in western Christianity, particularly in the Roman Catholic Church, for the Holy Eucharist or Eucharistic Sacrifice, the equivalent of the phrase Divine Liturgy used by Orthodox Christians.
The term "Mass" is derived from missa, a late Latin form of missio, itself a form of mittere ("to send"). The word occurs in the ordinary dismissal of the Latin Mass: Ite; missa est ("Go; you are sent forth"), and came into use in the Church of Rome in the fourth century. The form in English progressed from maesse before William the Conquerer's conquest of England to messe or masse in Middle English.
The word "Mass" is sometimes incorrectly used to refer to the Divine Liturgy by Orthodox Christians who may have been associated with communities who came from areas in central Europe that was affected by the Union of Brest-Litovsk.