\U"nit\, n. [Abbrev. from unity.]
1. A single thing or person.
2. (Arith.) The least whole number; one.
         Units are the integral parts of any large number.
                                               --I. Watts.
3. A gold coin of the reign of James I., of the value of
   twenty shillings. --Camden.
4. Any determinate amount or quantity (as of length, time,
   heat, value) adopted as a standard of measurement for
   other amounts or quantities of the same kind.
5. (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 determinate, 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.
{Complex unit} (Theory of Numbers), an imaginary number of
   the form a + broot{-1}, when a^{2} + b^{2} = 1.
{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, 1/4 is the unit of the fraction
   3/4.
{Integral unit}, the unit of integral numbers, or 1.
{Physical unit}, a value or magnitude conventionally adopted
   as a unit or standard in physical measurements. The
   various physical units are usually based on given units of
   length, mass, and time, and on the density or other
   properties of some substance, for example, water. See
   {Dyne}, {Erg}, {Farad}, {Ohm}, {Poundal}, etc.
{Unit deme} (Biol.), a unit of the inferior order or orders
   of individuality.
{Unit jar} (Elec.), a small, insulated Leyden jar, placed
   between the electrical machine and a larger jar or
   battery, so as to announce, by its repeated discharges,
   the amount of electricity passed into the larger jar.
{Unit of heat} (Physics), a determinate quantity of heat
   adopted as a unit of measure; a thermal unit (see under
   {Thermal}). Water is the substance generally employed, the
   unit being one gram or one pound, and the temperature
   interval one degree of the Centigrade or Fahrenheit scale.
   When referred to the gram, it is called the gram degree.
   The British unit of heat, or thermal unit, used by
   engineers in England and in the United States, is the
   quantity of heat necessary to raise one pound of pure
   water at and near its temperature of greatest density
   (39.1[deg] Fahr.) through one degree of the Fahrenheit
   scale. --Rankine.
{Unit of illumination}, the light of a sperm candle burning
   120 grains per hour. Standard gas, burning at the rate of
   five cubic feet per hour, must have an illuminating power
   equal to that of fourteen such candles.
{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 cent, 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
   avoirdupois for weight, the yard for length, the gallon of
   8.3389 pounds avoirdupois of water at 39.8[deg] Fahr.
   (about 231 cubic inches) for liquid measure, etc.; in
   Great Britain, the pound sterling, the pound troy, the
   yard, or 1/108719 part of the length of a second's
   pendulum at London, the gallon of 277.274 cubic inches,
   etc.; in the metric system, the meter, the liter, the
   gram, etc.
{Unit of power}. (Mach.) See {Horse power}.
{Unit of resistance}. (Elec.) See {Resistance}, n., 4, and
   {Ohm}.
{Unit of work} (Physics), the amount of work done by a unit
   force acting through a unit distance, or the amount
   required to lift a unit weight through a unit distance
   against gravitation. See {Erg}, {Foot Pound},
   {Kilogrammeter}.
{Unit stress} (Mech. Physics), stress per unit of area;
   intensity of stress. It is expressed in ounces, pounds,
   tons, etc., per square inch, square foot, or square yard,
   etc., or in atmospheres, or inches of mercury or water, or
   the like.