A set of independently defined units of measurement that forms the basis of a system of units. Such a set requires three mechanical units (usually of length, mass, and time) and one electrical unit; it has also been found convenient to treat certain other quantities as fundamental, even though they are not strictly independent. In the metric system the centimetre-gram-second (c.g.s.) system was replaced by the metre-kilogram-second (m.k.s.) system; the latter has now been adapted to provide the basis for SI units. In British Imperial units the foot-pound-second (f.p.s.) system was formerly used.
Subjects: Chemistry — Physics.