n. [L. densitas; cf. F.
densité.] 1. The quality of being
dense, close, or thick; compactness; -- opposed to
2. (Physics) The ratio of mass, or
quantity of matter, to bulk or volume, esp. as compared with the mass
and volume of a portion of some substance used as a
&fist; For gases the standard substance is hydrogen, at a
temperature of 0° Centigrade and a pressure of 760 millimeters.
For liquids and solids the standard is water at a temperature of
4° Centigrade. The density of solids and liquids is usually
called specific gravity, and the same is true of gases when
referred to air as a standard.
3. (Photog.) Depth of shade.