(mas, mäs) noun
1. An assemblage of things that collectively make one quantity.
2. A body of concrete matter; a lump.
3. The principal part of anything.
4. Extent of volume; bulk; size.
5. Physics The measure or expression of the inertia of a body, as indicated by the acceleration imparted to it when acted upon by a given force: it is the quotient of the weight of a body divided by the acceleration due to gravity.
—adjective
1. Of, for, or consisting of the public in general.
2. Done on a large scale: mass production.
—the masses The common people. See synonyms under MOB¹.
—v.t. & v.i. To form into a mass; assemble. [<OF masse <L massa, prob. <Gk. maza a barley cake] Synonyms (noun): aggregate, body, bulk, heap, lump, matter, substance, total, totality, whole. See AGGREGATE, HEAP, THRONG.

(mas, mäs) noun Eccl.
1. The eucharistic liturgy in the Roman Catholic and some Anglican churches, regarded as a commemoration or repetition of Christ's sacrifice on Calvary.
2. A celebration of this. See HIGH MASS, LOW MASS.
3. A musical setting for the fixed portions of this liturgy, as the Credo, Sanctus, Kyrie eleison, etc. Also Mass.
—black mass
1. A mass for the dead: so called because the celebrant wears black vestments.
2. A ceremony performed in so–called worship of Satan as a burlesque of the Christian mass. [OE mæsse <LL messa dismissal <L missa, pp. fem. of mittere send, dismiss <ite, missa est go, you are dismissed; said by the priest after the Eucharist is ended]