Metric system \Met"ric sys"tem\n.
A system of weights and measures originating in France, the
use of which is required by law in many countries, and
permitted in many others, including the United States; the
system is also called by its French name, {Le Syst[`e]me
International de Unit['e]s} (abbreviated SI). The principal
unit of length is the meter (see {Meter}). From this are
formed the are, the liter, the stere, the gram, etc. These
units, and others derived from them, are divided decimally,
and larger units are formed from multiples by 10, 100, 1,000,
and 10,000. The successive multiplies are designated by the
prefixes, deka- (formerly deca-), hecto-, kilo-, and myria-
(seldom used); successive parts by deci-, centi-, and milli-.
The prefixes mega- and micro- are used to denote a multiple
by one million, and the millionth part, respectively; giga-
and nano- denote multiples of one billion (1,000,000,000) and
one billionth, respectively. The prefix for one trillion
(1012) is tera, and for one trillionth (10-12) is pico; for
one quintillion (1015) peta, and for (10-15) (one
quintillionth) femto; for (10-18) atto. See the words formed
with these prefixes in the Vocabulary. For metric tables, see
p. 1682.
[1913 Webster +PJC]