n., v., & adj.
n. 1 a coherent body of matter of indefinite shape. 2 a dense aggregation of objects (a mass of fibres). 3 (in sing. or pl.; foll. by of) a large number or amount. 4 (usu. foll. by of) an unbroken expanse (of colour etc.). 5 (foll. by of) covered or abounding in (was a mass of cuts and bruises). 6 a main portion (of a painting etc.) as perceived by the eye. 7 (prec. by the) a the majority. b (in pl.) the ordinary people. 8 Physics the quantity of matter a body contains. 9 (attrib.) relating to, done by, or affecting large numbers of people or things; large-scale (mass audience; mass action; mass murder).
v.tr. & intr. 1 assemble into a mass or as one body (massed bands). 2 Mil. (with ref. to troops) concentrate or be concentrated. centre of mass a point representing the mean position of matter in a body or system. in the mass in the aggregate. law of mass action the principle that the rate of a chemical reaction is proportional to the masses of the reacting substances. mass defect the difference between the mass of an isotope and its mass number. mass energy a body's ability to do work according to its mass. mass media = MEDIA(1) 2. mass noun Gram. a noun that is not countable and cannot be used with the indefinite article or in the plural (e.g. bread). mass number the total number of protons and neutrons in a nucleus. mass observation Brit. the study and recording of the social habits and opinions of ordinary people. mass-produce produce by mass production. mass production the production of large quantities of a standardized article by a standardized mechanical process. mass spectrograph an apparatus separating isotopes, molecules, and molecular fragments according to mass by their passage in ionic form through electric and magnetic fields. mass spectrometer a device similar to a mass spectrograph but employing electrical detection. mass spectrum the distribution of ions shown by the use of a mass spectrograph or mass spectrometer. massless adj.
[ ME f. OF masse, masser f. L massa f. Gk maza barley-cake: perh. rel. to masso knead ]