A plastic or rubber mask through which oxygen may be breathed from a storage tank.

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

(Canada, US) A glass jar with a screw top, often used for preserving food.

plural of mass grave

A postgraduate degree usually in a non-science subject. / A person holding such a degree.

Deriving (especially sexual) pleasure from abuse, being punished, or dominated.

simple past tense and past participle of mass-produce

produced by mass production

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

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