Burial of multiple bodies in a mass grave

The mass of an atom. / (proscribed) atomic weight; the average mass of atoms of an element.

The pervasive surveillance of an entire population, or a substantial fraction thereof.

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.

(mathematics, physics) A point, near, or within a body at which the object's mass can be assumed to be concentrated; it coincides with the centroid for a body of uniform density, and with the centre of gravity in a uniform gravitational field.

US standard spelling of centre of mass.

(physics) The energy present in an object because of its mass

Collectively, the communications media, especially television, radio, and newspapers, that reach the mass of the people.

(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.

plural of mass extinction