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entropy
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English Dictionary: entropy by the DICT Development Group
4 results for entropy
From WordNet (r) 3.0 (2006) [wn]:
entropy
n
  1. (communication theory) a numerical measure of the uncertainty of an outcome; "the signal contained thousands of bits of information"
    Synonym(s): information, selective information, entropy
  2. (thermodynamics) a thermodynamic quantity representing the amount of energy in a system that is no longer available for doing mechanical work; "entropy increases as matter and energy in the universe degrade to an ultimate state of inert uniformity"
    Synonym(s): randomness, entropy, S
From Webster's Revised Unabridged Dictionary (1913) [web1913]:
   Entropy \En"tro*py\, n. [Gr. [?] a turning in; [?] in + [?] a
      turn, fr. [?] to turn.] (Thermodynamics)
      A certain property of a body, expressed as a measurable
      quantity, such that when there is no communication of heat
      the quantity remains constant, but when heat enters or leaves
      the body the quantity increases or diminishes. If a small
      amount, h, of heat enters the body when its temperature is t
      in the thermodynamic scale the entropy of the body is
      increased by h [?] t. The entropy is regarded as measured
      from some standard temperature and pressure. Sometimes called
      the thermodynamic function.
  
               The entropy of the universe tends towards a maximum.
                                                                              --Clausius.

From Webster's Revised Unabridged Dictionary (1913) [web1913]:
   Heat \Heat\, n. [OE. hete, h[91]te, AS. h[?]tu, h[?]to, fr.
      h[be]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
                     [bd]Tam o'Shanter.[b8]                        --J. C.
                                                                              Shairp.
  
      7. Utmost violence; rage; vehemence; as, the heat of battle
            or party. [bd]The heat of their division.[b8] --Shak.
  
      8. Agitation of mind; inflammation or excitement;
            exasperation. [bd]The head and hurry of his rage.[b8]
            --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.

From The Free On-line Dictionary of Computing (15Feb98) [foldoc]:
   entropy
  
      A measure of the disorder of a system.   Systems tend
      to go from a state of order (low entropy) to a state of
      maximum disorder (high entropy).
  
      The entropy of a system is related to the amount of
      {information} it contains.   A highly ordered system can be
      described using fewer {bit}s of information than a disordered
      one.   For example, a string containing one million "0"s can be
      described using {run-length encoding} as [("0", 1000000)]
      whereas a string of random symbols (e.g. bits, or characters)
      will be much harder, if not impossible, to compress in this
      way.
  
      {Shannon}'s formula gives the entropy H(M) of a message M in
      bits:
  
      H(M) = -log2 p(M)
  
      Where p(M) is the probability of message M.
  
      (1998-11-23)
  
  
No guarantee of accuracy or completeness!
©TU Chemnitz, 2006-2023
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