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 Système International de Unités (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.
A decimal system of weights and measures, adopted first in France, but now in widespread use throughout the world, and universally in science. Its official name in English is International System of Units. The basic units of measurement are the meter for distance (39.37") and the gram for mass (15.432 grains). Derived units include the liter (1.0908 U.S. dry quarts or 1.0567 U.S. liquid quarts), the are (114.9 square yards), and the stere (35.315 cubic feet)..The metric system is slowly moving into the printing world. Although printers and type founders have used point for 300 years and are slow to change, photo typesetting and transfer-type companies have been converting their type sizes to metric measure. Even some newspapers now measure columns in centimeters instead of in inches or agate lines. The equivalents appear below. See also PICA POINT 1 point equals .35 mm 1 mm equals 2.85 points. 72 points (6 picas) is approximately 25.24 mm (or 2.52 cms).