physics

Natural Nat"u*ral (?; 135), a. [OE. naturel, F. naturel, fr. L. naturalis, fr. natura. See {Nature}.] 1. Fixed or determined by nature; pertaining to the constitution of a thing; belonging to native character; according to nature; essential; characteristic; innate; not artificial, foreign, assumed, put on, or acquired; as, the natural growth of animals or plants; the natural motion of a gravitating body; natural strength or disposition; the natural heat of the body; natural color. [1913 Webster]

With strong natural sense, and rare force of will. --Macaulay. [1913 Webster]

2. Conformed to the order, laws, or actual facts, of nature; consonant to the methods of nature; according to the stated course of things, or in accordance with the laws which govern events, feelings, etc.; not exceptional or violent; legitimate; normal; regular; as, the natural consequence of crime; a natural death; anger is a natural response to insult. [1913 Webster]

What can be more natural than the circumstances in the behavior of those women who had lost their husbands on this fatal day? --Addison. [1913 Webster]

3. Having to do with existing system to things; dealing with, or derived from, the creation, or the world of matter and mind, as known by man; within the scope of human reason or experience; not supernatural; as, a natural law; natural science; history, theology. [1913 Webster]

I call that natural religion which men might know . . . by the mere principles of reason, improved by consideration and experience, without the help of revelation. --Bp. Wilkins. [1913 Webster]

4. Conformed to truth or reality; as: (a) Springing from true sentiment; not artificial or exaggerated; -- said of action, delivery, etc.; as, a natural gesture, tone, etc. (b) Resembling the object imitated; true to nature; according to the life; -- said of anything copied or imitated; as, a portrait is natural. [1913 Webster]

5. Having the character or sentiments properly belonging to one's position; not unnatural in feelings. [1913 Webster]

To leave his wife, to leave his babes, . . . He wants the natural touch. --Shak. [1913 Webster]

6. Connected by the ties of consanguinity. especially, Related by birth rather than by adoption; as, one's natural mother. ``Natural friends.'' --J. H. Newman. [1913 Webster +PJC]

7. Hence: Begotten without the sanction of law; born out of wedlock; illegitimate; bastard; as, a natural child. [1913 Webster]

8. Of or pertaining to the lower or animal nature, as contrasted with the higher or moral powers, or that which is spiritual; being in a state of nature; unregenerate. [1913 Webster]

The natural man receiveth not the things of the Spirit of God. --1 Cor. ii. 14. [1913 Webster]

9. (Math.) Belonging to, to be taken in, or referred to, some system, in which the base is 1; -- said of certain functions or numbers; as, natural numbers, those commencing at 1; natural sines, cosines, etc., those taken in arcs whose radii are 1. [1913 Webster]

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. (d) Neither flat nor sharp; -- of a tone. (e) Changed to the pitch which is neither flat nor sharp, by appending the sign [natural]; as, A natural. --Moore (Encyc. of Music). [1913 Webster +PJC]

11. Existing in nature or created by the forces of nature, in contrast to production by man; not made, manufactured, or processed by humans; as, a natural ruby; a natural bridge; natural fibers; a deposit of natural calcium sulfate. Opposed to {artificial}, {man-made}, {manufactured}, {processed} and {synthetic}. [WordNet sense 2] [PJC]

12. Hence: Not processed or refined; in the same statre as that existing in nature; as, natural wood; natural foods. [PJC]

{Natural day}, the space of twenty-four hours. --Chaucer. [1913 Webster]

{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, including 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; the natural sciences; 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 philosophy} and {moral philosophy}.

{Natural scale} (Mus.), a scale which is written without flats or sharps.

Note: 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}, the study of objects and phenomena existing in nature, especially biology, chemistry, physics and their interdisciplinary related sciences; {natural history}, in its broadest sense; -- used especially in contradistinction to {social science}, {mathematics}, {philosophy}, {mental science} or {moral science}.

{Natural selection} (Biol.), the operation of natural laws analogous, in their operation and results, to designed selection in breeding plants and animals, and resulting in the survival of the fittest; the elimination over time of species unable to compete in specific environments with other species more adapted to survival; -- the essential mechanism of evolution. The principle of natural selection is neutral with respect to the mechanism by which inheritable changes occur in organisms (most commonly thought to be due to mutation of genes and reorganization of genomes), but proposes that those forms which have become so modified as to be better adapted to the existing environment have tended to survive and leave similarly adapted descendants, while those less perfectly adapted have tended to die out through 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. [1913 Webster +PJC]

Syn: See {Native}. [1913 Webster]