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 + b-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, ¼ is the *unit* of the fraction
¾. -- **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° 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° 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.