Unit, n.

n. [Lat. unitum, from unitus, p. p. of unire, to unite, from unus, one.]

1Sense 1. A single thing or person; the least whole number; one.

Units are the integral parts of any large number. Watts.

2Sense 2. A gold coin of the reign of James I. Craig.

3Sense 3. (Math.) A single thing, as a magnitude or number, regarded as an undivided whole.

Abstract unit, the unit of numeration; one taken in the abstract; the number represented by 1. The term is used in distinction from concrete or denominate unit, that is, a unit in which the kind of thing is expressed; a unit of measure or value: as 1 foot, 1 dollar, 1 pound, and the like.—Duodecimal unit, a unit in the scale of numbers increasing or decreasing by twelves.—Fractional unit, the unit of a fraction; the reciprocal of the denominator; thus, ¼ is the unit of the fraction ¾.—Integral unit, the unit of integral numbers, or 1.—Unit of heat, the heat necessary to raise the temperature of one pound of ordinary cold water 1 degree Fahr.—Unit of measure (as of length, surface, volume, dry measure, liquid measure, money, weight, time, and the like), in general, a determinate quantity or magnitude of the kind designated, taken as a standard of comparison for others of the same kind, in assigning to them numerical values, as 1 foot, 1 yard, 1 mile, 1 square foot, 1 square yard, 1 cubic foot, 1 peck, 1 bushel, 1 gallon, 1 ounce, 1 pound, 1 hour, and the like; more specifically, the fundamental unit adopted in any system of weights, measures, or money, by which its several denominations are regulated, and which is itself defined by comparison with some known magnitude, either natural or empirical, as, in the United States, the dollar for money, the pound troy for weight, the yard for length, the gallon of 8.3389 pounds avoirdupois of water at 39.8° Fahr. (about 231 cubic inches) for liquid measure, &c.; in Great Britain, the pound sterling, the pound troy, the yard, or 1/1.08719 part of the length of a second’s pendulum at London, the gallon of 277.274 cubic inches, &c.; in France, the meter, the liter, the gramme, &c.—Unit of power, for steam-engines, the power required to raise 33,000 pounds one foot in a minute; a horse-power.—Unit of work (Mech.), the work expended in raising one pound to the height of one foot; called a foot-pound.