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

A mask worn by divers over the eyes or face to allow them to see clearly underwater, having a watertight seal around its edges to hold it securely to the face.

(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.

(education) A class, typically in a performing art such as music or drama, in which a teacher listens to and critiques the performance of individual students, one at a time, while the other students look on.

US standard spelling of centre of mass.

Of or pertaining to stonemasons or masonry. / Of or pertaining to freemasonry.

An action which demonstrates great skill or artistry.

An elevated area of south-central France.

plural of mass extinction

(evolutionary theory, geology) A sharp decrease in the total number of species in a relatively short period of time; specifically, a loss of ∼75% of all species on the planet over a geologically interval of less than 3 million years, as a result of a mass extinction event.