Theory

noun, plural theories.
1.
a coherent group of tested general propositions, commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena:
Einstein’s theory of relativity.
Synonyms: principle, law, doctrine.
2.
a proposed explanation whose status is still conjectural and subject to experimentation, in contrast to well-established propositions that are regarded as reporting matters of actual fact.
Synonyms: idea, notion hypothesis, postulate.
Antonyms: practice, verification, corroboration, substantiation.
3.
Mathematics. a body of principles, theorems, or the like, belonging to one subject:
number theory.
4.
the branch of a science or art that deals with its principles or methods, as distinguished from its practice:
music theory.
5.
a particular conception or view of something to be done or of the method of doing it; a system of rules or principles:
conflicting theories of how children best learn to read.
6.
contemplation or speculation:
the theory that there is life on other planets.
7.
guess or conjecture:
My theory is that he never stops to think words have consequences.
Idioms
8.
in theory, ideally; hypothetically:
In theory, mapping the human genome may lead to thousands of cures.
noun (pl) -ries
1.
a system of rules, procedures, and assumptions used to produce a result
2.
abstract knowledge or reasoning
3.
a speculative or conjectural view or idea: I have a theory about that
4.
an ideal or hypothetical situation (esp in the phrase in theory)
5.
a set of hypotheses related by logical or mathematical arguments to explain and predict a wide variety of connected phenomena in general terms: the theory of relativity
6.
a nontechnical name for hypothesis (sense 1)

theory the·o·ry (thē’ə-rē, thēr’ē)
n.

A systematically organized body of knowledge applicable in a relatively wide variety of circumstances, especially a system of assumptions, accepted principles, and rules of procedure devised to analyze, predict, or otherwise explain the nature or behavior of a specified set of phenomena.

Abstract reasoning; speculation.

theory
(thē’ə-rē, thîr’ē)
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. See Note at hypothesis.

theory definition

In science, an explanation or model that covers a substantial group of occurrences in nature and has been confirmed by a substantial number of experiments and observations. A theory is more general and better verified than a hypothesis. (See Big Bang theory, evolution, and relativity.)

The consensus, idea, plan, story, or set of rules that is currently being used to inform a behaviour. This usage is a generalisation and (deliberate) abuse of the technical meaning. “What’s the theory on fixing this TECO loss?” “What’s the theory on dinner tonight?” (“Chinatown, I guess.”) “What’s the current theory on letting lusers on during the day?” “The theory behind this change is to fix the following well-known screw….”
(1994-12-14)