Mass /ˈmæs/noun 3forms 1phrases 1 noun3 •The principal liturgical service of the Church, encompassing both a scripture service (Liturgy of the Word) and a eucharistic service (Liturgy of the Eucharist), which includes the consecration and oblation (offering) of the host and wine. •A similar ceremony offered by a number of Christian churches. •A musical composition set to portions, or all, of the Mass. formsMasses Phrases with Mass mass destructionKilling of large numbers of people.