A grave containing many corpses.

(physics, analytical chemistry) An analytical technique that measures the mass / charge ratio of the ions formed when a molecule or atom is ionized, vaporized and introduced into a vacuum. Mass spectrometry may also involve breaking molecules into fragments - thus enabling its structure to be determined.

(astronomy) A unit, equal to the mass of the sun, used to express the mass of other stars etc. 1 M_☉ = 2 × 10³⁰ kg.

(military) A body of troops held in military reserve by a general for striking a blow on an exposed flank or wherever the enemy reveals a weak spot.

simple past tense and past participle of mass-produce

(meteorology) A particular volume of air, especially one having a roughly uniform temperature, pressure and water vapour content.

produced by mass production

(transitive) To manufacture (something) on a large scale, especially by using assembly lines.

plural of mass grave

A Roman Catholic Mass celebrated in full ceremonial form, in which the celebrant is assisted by a deacon and a subdeacon and accompanied by acolytes, a thurifer, and a choir.