Theory meaning

thē'ə-rē, thîr'ē
An unproven concept.
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A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena.
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The definition of a theory is an idea to explain something, or a set of guiding principles.

Einstein's ideas about relativity are an example of the theory of relativity.

The scientific principles of evolution that are used to explain human life are an example of the theory of evolution.

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A formulation of apparent relationships or underlying principles of certain observed phenomena which has been verified to some degree.
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A speculative idea or plan as to how something might be done.
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A belief or principle that guides action or assists comprehension or judgment.

Staked out the house on the theory that criminals usually return to the scene of the crime.

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Abstract reasoning; speculation.

A decision based on experience rather than theory.

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The branch of a science or art consisting of its explanatory statements, accepted principles, and methods of analysis, as opposed to practice.

A fine musician who had never studied theory.

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A set of theorems that constitute a systematic view of a branch of mathematics.
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A systematic statement of principles involved.

The theory of equations in mathematics.

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(uncountable) The underlying principles or methods of a given technical skill, art etc., as opposed to its practice. [from 17th c.]
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(countable, logic) A set of axioms together with all statements derivable from them. Equivalently, a formal language plus a set of axioms (from which can then be derived theorems).

A theory is consistent if it has a model.

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A mental viewing; contemplation.
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That branch of an art or science consisting in a knowledge of its principles and methods rather than in its practice; pure, as opposed to applied, science, etc.
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A mere conjecture, or guess.
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A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena.
noun
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1
The branch of a science or art consisting of its explanatory statements, accepted principles, and methods of analysis, as opposed to practice.

A fine musician who had never studied theory.

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A set of theorems that constitute a systematic view of a branch of mathematics.
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Abstract reasoning; speculation.

A decision based on experience rather than theory.

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A belief or principle that guides action or assists comprehension or judgment.

Staked out the house on the theory that criminals usually return to the scene of the crime.

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An assumption based on limited information or knowledge; a conjecture.
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A set of statements or principles devised to explain a group of facts or phenomena. Most theories that are accepted by scientists have been repeatedly tested by experiments and can be used to make predictions about natural phenomena.
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A formulation of relationships or principles based on considerable factual evidence objectively analyzed to explain the operation of certain phenomena. A theory is in sharp contrast to pure speculation, which is an opinion based on incomplete evidence or information. See also law.
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(sciences) A coherent statement or set of ideas that explains observed facts or phenomena, or which sets out the laws and principles of something known or observed; a hypothesis confirmed by observation, experiment etc. [from 17th c.]
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(mathematics) A field of study attempting to exhaustively describe a particular class of constructs. [from 18th c.]

Knot theory classifies the mappings of a circle into 3-space.

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A hypothesis or conjecture. [from 18th c.]
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An assumption based on limited information or knowledge; a conjecture.
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Origin of theory

  • Late Latin theōria from Greek theōriā from theōros spectator probably theā a viewing -oros seeing (from horān to see)
    From American Heritage Dictionary of the English Language, 5th Edition
  • From Late Latin theōria, from Ancient Greek θεωρία (theōria, “contemplation, speculation, a looking at, things looked at"), from θεωρέω (theōreō, “I look at, view, consider, examine"), from θεωρός (theōros, “spectator"), from θέα (thea, “a view") + ὁράω (horaō, “I see,look").
    From Wiktionary