- 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.
- 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.
- Mathematics. a body of principles, theorems, or the like, belonging to one subject: number theory.
- the branch of a science or art that deals with its principles or methods, as distinguished from its practice: music theory.
- 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.
- contemplation or speculation: the theory that there is life on other planets.
- guess or conjecture: My theory is that he never stops to think words have consequences.
- in theory, ideally; hypothetically: In theory, mapping the human genome may lead to thousands of cures.
Origin of theory
Examples from the Web for theories
But privately, it is listening to other theories, including those about an inside job.FBI Won’t Stop Blaming North Korea for Sony Hack -- Despite New Evidence
December 30, 2014
He acknowledged the theories but his voice lacked conviction.Alfred Hitchcock’s Fade to Black: The Great Director’s Final Days
December 13, 2014
And probably the truth lies somewhere in between the two theories.Blood in the Sand: When James Jones Wrote a Grunt’s View of D-Day
November 15, 2014
His theories and interpretations are often astonishingly insightful.
This makes a certain sense given his deep knowledge of the theories of previous scientists.
These theories were also in their consequences far-reaching.'Tis Sixty Years Since
Charles Francis Adams
Many of his theories are no doubt impracticable and unsound.The Works of Whittier, Volume VII (of VII)
John Greenleaf Whittier
Unconsciously his whole practice began to refute his theories.
We must take them into our alliance, or they will destroy all our theories of self-government.
Other theories with regard to the origin of the hundred have been suggested.English Villages
P. H. Ditchfield
- a system of rules, procedures, and assumptions used to produce a result
- abstract knowledge or reasoning
- a speculative or conjectural view or ideaI have a theory about that
- an ideal or hypothetical situation (esp in the phrase in theory)
- a set of hypotheses related by logical or mathematical arguments to explain and predict a wide variety of connected phenomena in general termsthe theory of relativity
- a nontechnical name for hypothesis (def. 1)
Word Origin and History for theories
1590s, "conception, mental scheme," from Late Latin theoria (Jerome), from Greek theoria "contemplation, speculation, a looking at, things looked at," from theorein "to consider, speculate, look at," from theoros "spectator," from thea "a view" + horan "to see" (see warrant (n.)). Sense of "principles or methods of a science or art (rather than its practice)" is first recorded 1610s. That of "an explanation based on observation and reasoning" is from 1630s.
adsorption theory of narcosis
- The theory that a drug becomes concentrated at the surface of the cell as a result of adsorption and thus alters the cell wall permeability and the cell's metabolism.
- 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.
Big Bang theory
In astronomy, a theory according to which the universe began billions of years ago in a single event, similar to an explosion. There is evidence for the Big Bang theory in the observed red shift of distant galaxies, which indicates that they are moving away from the Earth, in the existence of cosmic microwave background, and from other data. The Big Bang theory of the origin of the universe is accepted by most astronomers today.