Source : Webster's Revised Unabridged Dictionary (1913)

   10. (Mus.)
       (a) Produced by natural organs, as those of the human
           throat, in distinction from instrumental music.
       (b) Of or pertaining to a key which has neither a flat
           nor a sharp for its signature, as the key of C major.
       (c) Applied to an air or modulation of harmony which
           moves by easy and smooth transitions, digressing but
           little from the original key. --Moore (Encyc. of
           Music).

   {Natural day}, the space of twenty-four hours. --Chaucer.

   {Natural fats}, {Natural gas}, etc. See under {Fat}, {Gas}.
      etc.

   {Natural Harmony} (Mus.), the harmony of the triad or common
      chord.

   {Natural history}, in its broadest sense, a history or
      description of nature as a whole, incuding the sciences of
      {botany}, {zo["o]logy}, {geology}, {mineralogy},
      {paleontology}, {chemistry}, and {physics}. In recent
      usage the term is often restricted to the sciences of
      botany and zo["o]logy collectively, and sometimes to the
      science of zoology alone.

   {Natural law}, that instinctive sense of justice and of right
      and wrong, which is native in mankind, as distinguished
      from specifically revealed divine law, and formulated
      human law.

   {Natural modulation} (Mus.), transition from one key to its
      relative keys.

   {Natural order}. (Nat. Hist.) See under {order}.

   {Natural person}. (Law) See under {person}, n.

   {Natural philosophy}, originally, the study of nature in
      general; in modern usage, that branch of physical science,
      commonly called {physics}, which treats of the phenomena
      and laws of matter and considers those effects only which
      are unaccompanied by any change of a chemical nature; --
      contrasted with mental and moral philosophy.

   {Natural scale} (Mus.), a scale which is written without
      flats or sharps. Model would be a preferable term, as less
      likely to mislead, the so-called artificial scales (scales
      represented by the use of flats and sharps) being equally
      natural with the so-called natural scale

   {Natural science}, natural history, in its broadest sense; --
      used especially in contradistinction to mental or moral
      science.

   {Natural selection} (Biol.), a supposed operation of natural
      laws analogous, in its operation and results, to designed
      selection in breeding plants and animals, and resulting in
      the survival of the fittest. The theory of natural
      selection supposes that this has been brought about mainly
      by gradual changes of environment which have led to
      corresponding changes of structure, and that those forms
      which have become so modified as to be best adapted to the
      changed environment have tended to survive and leave
      similarly adapted descendants, while those less perfectly
      adapted have tended to die out though lack of fitness for
      the environment, thus resulting in the survival of the
      fittest. See {Darwinism}.

   {Natural system} (Bot. & Zo["o]l.), a classification based
      upon real affinities, as shown in the structure of all
      parts of the organisms, and by their embryology.

            It should be borne in mind that the natural system
            of botany is natural only in the constitution of its
            genera, tribes, orders, etc., and in its grand
            divisions.                            --Gray.
      

   {Natural theology}, or {Natural religion}, that part of
      theological science which treats of those evidences of the
      existence and attributes of the Supreme Being which are
      exhibited in nature; -- distinguished from revealed
      religion. See Quotation under {Natural}, a., 3.

   {Natural vowel}, the vowel sound heard in urn, furl, sir,
      her, etc.; -- so called as being uttered in the easiest
      open position of the mouth organs. See {Neutral vowel},
      under {Neutral} and Guide to Pronunciation, [sect] 17.

   Syn: See {Native}.