1. [n]  utility to warm a building; "the heating system wasn't working"; "they have radiant heating"
2. [n]  intense passion or emotion
3. [n]  the presence of heat
4. [n]  the sensation caused by heat energy
5. [n]  a form of energy that is transferred by a difference in temperature
6. [n]  applies to nonhuman mammals: a state or period of heightened sexual arousal and activity
7. [v]  make hot or hotter; "heat the soup"
8. [v]  gain heat or get hot; "The room heated up quickly"
9. [v]  arouse or excite feelings and passions; "The ostentatious way of living of the rich ignites the hatred of the poor"; "The refugees' fate stirred up compassion around the world"; "Wake old feelings of hatred"
10. [v]  provide with heat; "heat the house"

Heat
Simple text and experiments describe and demonstrate the principles of heat and how heat energy is produced.

more details ...

1. \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.
   

2. \Heat\, v. t. [imp. & p. p. {Heated}; p. pr. & vb. n.
   {Heating}.] [OE. heten, AS. h?tan, fr. h[=a]t hot. See
   {Hot}.]
   1. To make hot; to communicate heat to, or cause to grow
      warm; as, to heat an oven or furnace, an iron, or the
      like.
            Heat me these irons hot.              --Shak.
   2. To excite or make hot by action or emotion; to make
      feverish.
            Pray, walk softly; do not heat your blood. --Shak.
   3. To excite ardor in; to rouse to action; to excite to
      excess; to inflame, as the passions.
            A noble emulation heats your breast.  --Dryden.
   

3. \Heat\, v. i.
   1. To grow warm or hot by the action of fire or friction,
      etc., or the communication of heat; as, the iron or the
      water heats slowly.
   2. To grow warm or hot by fermentation, or the development of
      heat by chemical action; as, green hay heats in a mow, and
      manure in the dunghill.
   

4. \Heat\, imp. & p. p. of {Heat}.
   Heated; as, the iron though heat red-hot. [Obs. or Archaic.]
   --Shak.