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theory Idioms & Phrases


arrhenius theory of dissociation

  • noun (chemistry) theory that describes aqueous solutions in terms of acids (which dissociate to give hydrogen ions) and bases (which dissociate to give hydroxyl ions); the product of an acid and a base is a salt and water
    theory of dissociation; Arrhenius theory of dissociation.
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association theory

  • noun (psychology) a theory that association is the basic principle of mental activity
    associationism.
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Atomic theory

  • noun a theory of the structure of the atom
  • noun (chemistry) any theory in which all matter is composed of tiny discrete finite indivisible indestructible particles
    atomism; atomic theory; atomist theory.
    • the ancient Greek philosophers Democritus and Epicurus held atomic theories of the universe
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  • or the Doctrine of definite proportions (Chem.), teaches that chemical combinations take place between the supposed ultimate particles or atoms of bodies, in some simple ratio, as of one to one, two to three, or some other, always expressible in whole numbers.
Webster 1913

Atomic theory, Binary theory

  • etc. See under Atomic, Binary, etc.
Webster 1913

atomist theory

  • noun (chemistry) any theory in which all matter is composed of tiny discrete finite indivisible indestructible particles
    atomism; atomic theory; atomist theory.
    • the ancient Greek philosophers Democritus and Epicurus held atomic theories of the universe
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atomistic theory

  • noun (chemistry) any theory in which all matter is composed of tiny discrete finite indivisible indestructible particles
    atomism; atomic theory; atomist theory.
    • the ancient Greek philosophers Democritus and Epicurus held atomic theories of the universe
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big bang theory

  • noun (cosmology) the theory that the universe originated sometime between 10 billion and 20 billion years ago from the cataclysmic explosion of a small volume of matter at extremely high density and temperature
    big bang theory.
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big-bang theory

  • noun (cosmology) the theory that the universe originated sometime between 10 billion and 20 billion years ago from the cataclysmic explosion of a small volume of matter at extremely high density and temperature
    big bang theory.
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Binary theory

  • (Chem.), the theory that all chemical compounds consist of two constituents of opposite and unlike qualities.
Webster 1913

bohr theory

  • noun (physics) a theory of atomic structure that combined Rutherford's model with the quantum theory; electrons orbiting a nucleus can only be in certain stationary energy states and light is emitted when electrons jump from one energy state to another
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Cell theory

  • noun (biology) the theory that cells form the fundamental structural and functional units of all living organisms; proposed in 1838 by Matthias Schleiden and by Theodor Schwann
    cell doctrine.
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  • . (Biol.) See Cellular theory, under Cellular.
Webster 1913

Cellular theory, ∨ Cell theory

  • (Biol.), a theory, according to which the essential element of every tissue, either vegetable or animal, is a cell; the whole series of cells having been formed from the development of the germ cell and by differentiation converted into tissues and organs which, both in plants ans animals, are to be considered as a mass of minute cells communicating with each other.
Webster 1913

communication theory

  • noun the discipline that studies the principles of transmiting information and the methods by which it is delivered (as print or radio or television etc.)
    communications.
    • communications is his major field of study
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continuous creation theory

  • noun (cosmology) the theory that the universe maintains a constant average density with matter created to fill the void left by galaxies that are receding from each other
    continuous creation theory.
    • the steady state theory has been abandoned in favor of the big bang theory
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Corpuscular theory

  • noun (physics) the theory that light is transmitted as a stream of particles
    corpuscular theory.
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  • (Opt.), the theory enunciated by Sir Isaac Newton, that light consists in the emission and rapid progression of minute particles or corpuscles. The theory is now generally rejected, and supplanted by the undulatory theory.
Webster 1913

corpuscular theory of light

  • noun (physics) the theory that light is transmitted as a stream of particles
    corpuscular theory.
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Development theory

  • (Biol.), the doctrine that animals and plants possess the power of passing by slow and successive stages from a lower to a higher state of organization, and that all the higher forms of life now in existence were thus developed by uniform laws from lower forms, and are not the result of special creative acts. See the Note under Darwinian.
Webster 1913

Domino theory

  • noun the political theory that if one nation comes under communist control then neighboring nations will also come under communist control
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  • . A political theory current in the 1960's, according to which the conversion of one country in South Asia to communism will start a sequential process causing all Asian countries to convert to Communism. The apparent assumption was that an Asian country with a Western orientation was as politically unstable as a domino standing on edge. Used by some as a justification for American involvement in the Vietnam war, 1964-1972.
Webster 1913

Dualistic system ∨ theory

  • (Chem.), the theory, originated by Lavoisier and developed by Berzelius, that all definite compounds are binary in their nature, and consist of two distinct constituents, themselves simple or complex, and possessed of opposite chemical or electrical affinities.
Webster 1913

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.
Webster 1913

economic theory

  • noun (economics) a theory of commercial activities (such as the production and consumption of goods)
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einstein's general theory of relativity

  • noun a generalization of special relativity to include gravity (based on the principle of equivalence)
    Einstein's general theory of relativity; general relativity; general relativity theory.
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einstein's special theory of relativity

  • noun a physical theory of relativity based on the assumption that the speed of light in a vacuum is a constant and the assumption that the laws of physics are invariant in all inertial systems
    special relativity theory; Einstein's special theory of relativity; special relativity.
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einstein's theory of relativity

  • noun (physics) the theory that space and time are relative concepts rather than absolute concepts
    Einstein's theory of relativity; relativity; relativity theory.
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Electro-magnetic theory of light

  • (Physics), a theory of light which makes it consist in the rapid alternation of transient electric currents moving transversely to the direction of the ray.
Webster 1913

Emission theory

  • (Physics), the theory of Newton, regarding light as consisting of emitted particles or corpuscles. See Corpuscular theory, under Corpuscular.
Webster 1913

Fermentation theory of disease

  • (Biol. & Med.), the theory that most if not all, infectious or zymotic disease are caused by the introduction into the organism of the living germs of ferments, or ferments already developed (organized ferments), by which processes of fermentation are set up injurious to health. See Germ theory.
Webster 1913

field theory

  • noun (physics) a theory that explains a physical phenomenon in terms of a field and the manner in which it interacts with matter or with other fields
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galois theory

  • noun group theory applied to the solution of algebraic equations
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game theory

  • noun (economics) a theory of competition stated in terms of gains and losses among opposing players
    game theory.
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general relativity theory

  • noun a generalization of special relativity to include gravity (based on the principle of equivalence)
    Einstein's general theory of relativity; general relativity; general relativity theory.
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general theory of relativity

  • noun a generalization of special relativity to include gravity (based on the principle of equivalence)
    Einstein's general theory of relativity; general relativity; general relativity theory.
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Germ theory

  • noun (medicine) the theory that all contagious diseases are caused by microorganisms
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  • (Biol.), the theory that living organisms can be produced only by the evolution or development of living germs or seeds. See Biogenesis, and Abiogenesis. As applied to the origin of disease, the theory claims that the zymotic diseases are due to the rapid development and multiplication of various bacteria, the germs or spores of which are either contained in the organism itself, or transferred through the air or water. See Fermentation theory.
Webster 1913

Glacial theory ∨ hypothesis

  • . (Geol.) See Glacier theory, under Glacier.
Webster 1913

Glacier theory

  • (Geol.), the theory that large parts of the frigid and temperate zones were covered with ice during the glacial, or ice, period, and that, by the agency of this ice, the loose materials on the earth's surface, called drift or diluvium, were transported and accumulated.
Webster 1913

gravitational theory

  • noun (physics) the theory that any two particles of matter attract one another with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them
    theory of gravitation; gravitational theory; Newton's theory of gravitation.
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group theory

  • noun the branch of mathematics dealing with groups
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holistic theory

  • noun the theory that the parts of any whole cannot exist and cannot be understood except in their relation to the whole
    holism.
    • holism holds that the whole is greater than the sum of its parts
    • holistic theory has been applied to ecology and language and mental states
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in theory

  • adverb with regard to fundamentals although not concerning details
    in principle; in essence.
    • in principle, we agree
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information theory

  • noun (computer science) a statistical theory dealing with the limits and efficiency of information processing
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kinetic theory

  • noun (physics) a theory that gases consist of small particles in random motion
    kinetic theory.
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kinetic theory of gases

  • noun (physics) a theory that gases consist of small particles in random motion
    kinetic theory.
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kinetic theory of heat

  • noun a theory that the temperature of a body increases when kinetic energy increases
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m-theory

  • noun (particle physics) a theory that involves an eleven-dimensional universe in which the weak and strong forces and gravity are unified and to which all the string theories belong
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malthusian theory

  • noun Malthus' theory that population increase would outpace increases in the means of subsistence
    Malthusianism.
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Neptunian theory

  • (Geol.), the theory of Werner, which referred the formation of all rocks and strata to the agency of water; opposed to the Plutonic theory.
Webster 1913

newton's theory of gravitation

  • noun (physics) the theory that any two particles of matter attract one another with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them
    theory of gravitation; gravitational theory; Newton's theory of gravitation.
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Newtonian theory of light

  • . See Note under Light.
Webster 1913

ostwald's theory of indicators

  • noun (chemistry) the theory that all indicators are either weak acids or weak bases in which the color of the ionized form is different from the color before dissociation
    Ostwald's theory of indicators.
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philosophical theory

  • noun a doctrine accepted by adherents to a philosophy
    philosophical doctrine.
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plate tectonic theory

  • noun the branch of geology studying the folding and faulting of the earth's crust
    plate tectonics; tectonics.
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Plutonic theory

  • . (Geol.) See Plutonism.
Webster 1913

political theory

  • noun an orientation that characterizes the thinking of a group or nation
    ideology; political orientation.
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probability theory

  • noun the branch of applied mathematics that deals with probabilities
    probability theory.
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quantum field theory

  • noun the branch of quantum physics that is concerned with the theory of fields; it was motivated by the question of how an atom radiates light as its electrons jump from excited states
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quantum theory

  • noun (physics) a physical theory that certain properties occur only in discrete amounts (quanta)
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relativity theory

  • noun (physics) the theory that space and time are relative concepts rather than absolute concepts
    Einstein's theory of relativity; relativity; relativity theory.
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scientific theory

  • noun a theory that explains scientific observations
    • scientific theories must be falsifiable
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set theory

  • noun the branch of pure mathematics that deals with the nature and relations of sets
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special relativity theory

  • noun a physical theory of relativity based on the assumption that the speed of light in a vacuum is a constant and the assumption that the laws of physics are invariant in all inertial systems
    special relativity theory; Einstein's special theory of relativity; special relativity.
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special theory of relativity

  • noun a physical theory of relativity based on the assumption that the speed of light in a vacuum is a constant and the assumption that the laws of physics are invariant in all inertial systems
    special relativity theory; Einstein's special theory of relativity; special relativity.
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steady state theory

  • noun (cosmology) the theory that the universe maintains a constant average density with matter created to fill the void left by galaxies that are receding from each other
    continuous creation theory.
    • the steady state theory has been abandoned in favor of the big bang theory
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Sthenic theory

  • . See Stimulism (a).
Webster 1913

string theory

  • noun (particle physics) a theory that postulates that subatomic particles are one-dimensional strings
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theory of dissociation

  • noun (chemistry) theory that describes aqueous solutions in terms of acids (which dissociate to give hydrogen ions) and bases (which dissociate to give hydroxyl ions); the product of an acid and a base is a salt and water
    theory of dissociation; Arrhenius theory of dissociation.
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theory of electrolytic dissociation

  • noun (chemistry) theory that describes aqueous solutions in terms of acids (which dissociate to give hydrogen ions) and bases (which dissociate to give hydroxyl ions); the product of an acid and a base is a salt and water
    theory of dissociation; Arrhenius theory of dissociation.
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theory of evolution

  • noun (biology) a scientific theory of the origin of species of plants and animals
    evolutionism; theory of evolution.
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theory of games

  • noun (economics) a theory of competition stated in terms of gains and losses among opposing players
    game theory.
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theory of gravitation

  • noun (physics) the theory that any two particles of matter attract one another with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them
    theory of gravitation; gravitational theory; Newton's theory of gravitation.
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theory of gravity

  • noun (physics) the theory that any two particles of matter attract one another with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them
    theory of gravitation; gravitational theory; Newton's theory of gravitation.
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theory of indicators

  • noun (chemistry) the theory that all indicators are either weak acids or weak bases in which the color of the ionized form is different from the color before dissociation
    Ostwald's theory of indicators.
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theory of inheritance

  • noun (biology) a theory of how characteristics of one generation are derived from earlier generations
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theory of organic evolution

  • noun (biology) a scientific theory of the origin of species of plants and animals
    evolutionism; theory of evolution.
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theory of preformation

  • noun a theory (popular in the 18th century and now discredited) that an individual develops by simple enlargement of a tiny fully formed organism (a homunculus) that exists in the germ cell
    preformation.
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theory of probability

  • noun the branch of applied mathematics that deals with probabilities
    probability theory.
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theory of punctuated equilibrium

  • noun a theory of evolution holding that evolutionary change in the fossil record came in fits and starts rather than in a steady process of slow change
    punctuated equilibrium.
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theory of relativity

  • noun (physics) the theory that space and time are relative concepts rather than absolute concepts
    Einstein's theory of relativity; relativity; relativity theory.
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theory-based

  • adjective satellite based in theory rather than experiment
    • theory-based arguments and positions
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undulatory theory

  • noun (physics) the theory that light is transmitted as waves
    wave theory; undulatory theory.
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Undulatory theory, ∨ Wave theory

  • (of light) (Opt.), that theory which regards its various phenomena as due to undulations in an ethereal medium, propagated from the radiant with immense, but measurable, velocities, and producing different impressions on the retina according to their amplitude and frequency, the sensation of brightness depending on the former, that of color on the latter. The undulations are supposed to take place, not in the direction of propagation, as in the air waves constituting sound, but transversely, and the various phenomena of refraction, polarization, interference, etc., are attributable to the different affections of these undulations in different circumstances of propagation. It is computed that the frequency of the undulations corresponding to the several colors of the spectrum ranges from 458 millions of millions per second for the extreme red ray, to 727 millions of millions for the extreme violet, and their lengths for the same colors, from the thirty-eight thousandth to the sixty thousandth part of an inch. The theory of ethereal undulations is applicable not only to the phenomena of light, but also to those of heat.
Webster 1913

Unitary theory

  • (Chem.), the modern theory that the molecules of all complete compounds are units, whose parts are bound together in definite structure, with mutual and reciprocal influence on each other, and are not mere aggregations of more or less complex groups; distinguished from the dualistic theory.
Webster 1913

Wave theory

  • noun (physics) the theory that light is transmitted as waves
    wave theory; undulatory theory.
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  • . (Physics) See Undulatory theory, under Undulatory.
Webster 1913

wave theory of light

  • noun (physics) the theory that light is transmitted as waves
    wave theory; undulatory theory.
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Wave-line system, Wave-line theory

  • (Shipbuilding), a system or theory of designing the lines of a vessel, which takes into consideration the length and shape of a wave which travels at a certain speed.
Webster 1913