A unified body of matter with no specific shape: a mass of clay. A grouping of individual parts or elements that compose a unified body of unspecified size or quantity: "Take mankind in mass, and for the most part, they seem a mob of unnecessary duplicates\u201d ( Herman Melville). A large but nonspecific amount or number: a mass of bruises. A lump or aggregate of coherent material: a cancerous mass. The principal part; the majority: the mass of the continent. The physical volume or bulk of a solid body. Physics A property of matter equal to the measure of an object's resistance to changes in either the speed or direction of its motion. The mass of an object is not dependent on gravity and therefore is different from but proportional to its weight. An area of unified light, shade, or color in a painting. Pharmacology A thick, pasty mixture containing drugs from which pills are formed. The body of common people or people of low socioeconomic status: "Give me your tired, your poor,/Your huddled masses yearning to breathe free\u201d ( Emma Lazarus). To gather or be gathered into a mass. Of, relating to, characteristic of, directed at, or attended by a large number of people: mass education; mass communication. Done or carried out on a large scale: mass production. Total; complete: The mass result is impressive.