n A quantity of mattercohere|cohering together so as to make one body, or an aggregation of particles or things which collectively make one body or quantity, usually of considerable size; as, a mass of ore, metal, sand, or water.
n (physics) The quantity of matter which a body contains, irrespective of its bulk or volume. It is one of four fundamental property | properties of matter. It is measured in kilograms in the SI system of measurement.