Source : Webster's Revised Unabridged Dictionary (1913)

Unit \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.

Heat \Heat\, n. [OE. hete, h[ae]te, AS. h?tu, h?to, fr. h[=a]t
   hot; akin to OHG. heizi heat, Dan. hede, Sw. hetta. See
   {Hot}.]
   1. A force in nature which is recognized in various effects,
      but especially in the phenomena of fusion and evaporation,
      and which, as manifested in fire, the sun's rays,
      mechanical action, chemical combination, etc., becomes
      directly known to us through the sense of feeling. In its
      nature heat is a mode if motion, being in general a form
      of molecular disturbance or vibration. It was formerly
      supposed to be a subtile, imponderable fluid, to which was
      given the name caloric.

   Note: As affecting the human body, heat produces different
         sensations, which are called by different names, as
         heat or sensible heat, warmth, cold, etc., according to
         its degree or amount relatively to the normal
         temperature of the body.

   2. The sensation caused by the force or influence of heat
      when excessive, or above that which is normal to the human
      body; the bodily feeling experienced on exposure to fire,
      the sun's rays, etc.; the reverse of cold.

   3. High temperature, as distinguished from low temperature,
      or cold; as, the heat of summer and the cold of winter;
      heat of the skin or body in fever, etc.

            Else how had the world . . . Avoided pinching cold
            and scorching heat!                   --Milton.

   4. Indication of high temperature; appearance, condition, or
      color of a body, as indicating its temperature; redness;
      high color; flush; degree of temperature to which
      something is heated, as indicated by appearance,
      condition, or otherwise.

            It has raised . . . heats in their faces. --Addison.

            The heats smiths take of their iron are a blood-red
            heat, a white-flame heat, and a sparking or welding
            heat.                                 --Moxon.

   5. A single complete operation of heating, as at a forge or
      in a furnace; as, to make a horseshoe in a certain number
      of heats.

   6. A violent action unintermitted; a single effort; a single
      course in a race that consists of two or more courses; as,
      he won two heats out of three.

            Many causes . . . for refreshment betwixt the heats.
                                                  --Dryden.

            [He] struck off at one heat the matchless tale of
            ``Tam o'Shanter.''                    --J. C.
                                                  Shairp.

   7. Utmost violence; rage; vehemence; as, the heat of battle
      or party. ``The heat of their division.'' --Shak.

   8. Agitation of mind; inflammation or excitement;
      exasperation. ``The head and hurry of his rage.'' --South.

   9. Animation, as in discourse; ardor; fervency.

            With all the strength and heat of eloquence.
                                                  --Addison.

   10. Sexual excitement in animals.

   11. Fermentation.

   {Animal heat}, {Blood heat}, {Capacity for heat}, etc. See
      under {Animal}, {Blood}, etc.

   {Atomic heat} (Chem.), the product obtained by multiplying
      the atomic weight of any element by its specific heat. The
      atomic heat of all solid elements is nearly a constant,
      the mean value being 6.4.

   {Dynamical theory of heat}, that theory of heat which assumes
      it to be, not a peculiar kind of matter, but a peculiar
      motion of the ultimate particles of matter.

   {Heat engine}, any apparatus by which a heated substance, as
      a heated fluid, is made to perform work by giving motion
      to mechanism, as a hot-air engine, or a steam engine.

   {Heat producers}. (Physiol.) See under {Food}.

   {Heat rays}, a term formerly applied to the rays near the red
      end of the spectrum, whether within or beyond the visible
      spectrum.

   {Heat weight} (Mech.), the product of any quantity of heat by
      the mechanical equivalent of heat divided by the absolute
      temperature; -- called also {thermodynamic function}, and
      {entropy}.

   {Mechanical equivalent of heat}. See under {Equivalent}.

   {Specific heat of a substance} (at any temperature), the
      number of units of heat required to raise the temperature
      of a unit mass of the substance at that temperature one
      degree.

   {Unit of heat}, the quantity of heat required to raise, by
      one degree, the temperature of a unit mass of water,
      initially at a certain standard temperature. The
      temperature usually employed is that of 0[deg] Centigrade,
      or 32[deg] Fahrenheit.