prin·ci·ple | \ˈprin(t)-s(ə-)pəl, -sə-bəl\

Definition of principle 

1a : a comprehensive and fundamental law, doctrine, or assumption

b(1) : a rule or code of conduct

(2) : habitual devotion to right principles a man of principle

c : the laws or facts of nature underlying the working of an artificial device

2 : a primary source : origin

3a : an underlying faculty or endowment such principles of human nature as greed and curiosity

b : an ingredient (such as a chemical) that exhibits or imparts a characteristic quality

4 capitalized, Christian Science : a divine principle : god

in principle

: with respect to fundamentals prepared to accept the proposition in principle

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Principle vs. Principal: Usage Guide

Although nearly every handbook and many dictionaries warn against confusing principle and principal, many people still do. Principle is only a noun; principal is both adjective and noun. If you are unsure which noun you want, read the definitions in this dictionary.

Principle vs. Principal

Yes, these two words are confusing; we see evidence of the misuse of both in newspapers and books which have been overseen by professional editors, so don’t feel bad if you have trouble with them. Principle only functions as a noun (such as “a comprehensive and fundamental law, doctrine, or assumption”); if you want it to be an adjective you must use the word principled. Principal, on the other hand, may function as a noun (such as the head of a school) or as an adjective (meaning “most important”). 

Examples of principle in a Sentence

Urban guerrilla warfare was futile against a thermonuclear superstate that would stop at nothing to defend the profit principle. — Philip Roth, American Pastoral, 1997 Better, of course, to take a higher road, operate on the principle of service and see if things don't turn out better … — Richard Ford, Independence Day, 1995 Pointlessness was life's principle, and it spread its sadness. — Arthur Miller, Timebends, 1987 His investment strategy is based on the principle that the stock market offers the best returns for long-term investors. the basic principles of hydraulics
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Recent Examples on the Web

But one is that welfare states have often diverged from the liberal principles that underpinned them. The Economist, "Capitalism needs a welfare state to survive," 12 July 2018 These basic market-clearing principles cannot operate in a single-payer system. Sally C. Pipes, Fortune, "Why Does the Left Want Universal Health Care? Britain’s Is on Its Deathbed," 10 July 2018 The older industrial communities were built on innovation and entrepreneurship, the same principles needed to create a strong technology ecosystem throughout North Carolina. charlotteobserver, "Ashley Christensen," 3 July 2018 The second principle of conservatism is to put country before party. The Economist, "The Conservative Party has trashed the basic principles of conservatism," 12 July 2018 The principle has been in the news a few times recently. Ciara Nugent, Time, "Meghan Markle Is Being Drawn Into the Irish Abortion Debate. Here's Why That's a Big Deal," 11 July 2018 Or changing or moving them into a smaller ... That principle is exactly what most IT organizations need to be able to have within their environment. Recode Staff, Recode, "Full transcript: Box CEO Aaron Levie on Recode Decode," 11 July 2018 So the question is not whether the nominee can read unambiguous words, but how the nominee handles ambiguity and contradiction, what the nominee’s core constitutional principles are, and how the nominee exercises discretion. Carolyn Shapiro, Fortune, "Brett Kavanaugh Said Judges Should Just Follow the Law. Here’s Why That’s Bull," 10 July 2018 The principle of the deal is that the move is not solely about money - Ronaldo is a rich enough man - but the respect and worth that the money would symbolise, for a player who above all has a pathological need to be wanted and valued., "Juventus 'Begin' Stunning €120m Cristiano Ronaldo Move With Real Madrid Prepared to Negotiate," 3 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'principle.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of principle

14th century, in the meaning defined at sense 1a

History and Etymology for principle

Middle English, from Middle French principe, principle, from Old French, from Latin principium beginning, from princip-, princeps initiator — more at prince

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Statistics for principle

Last Updated

7 Oct 2018

Look-up Popularity

Time Traveler for principle

The first known use of principle was in the 14th century

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More Definitions for principle



English Language Learners Definition of principle

: a moral rule or belief that helps you know what is right and wrong and that influences your actions

: a basic truth or theory : an idea that forms the basis of something

: a law or fact of nature that explains how something works or why something happens


prin·ci·ple | \ˈprin-sə-pəl \

Kids Definition of principle

1 : a general or basic truth on which other truths or theories can be based scientific principles

2 : a rule of conduct based on beliefs of what is right and wrong

3 : a law or fact of nature which makes possible the working of a machine or device the principle of magnetism


prin·ci·ple | \ˈprin(t)-sə-pəl \

Medical Definition of principle 

1 : a comprehensive and fundamental law, doctrine, or assumption

2 : an ingredient (as a chemical) that exhibits or imparts a characteristic quality the active principle of a drug

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Comments on principle

What made you want to look up principle? Please tell us where you read or heard it (including the quote, if possible).


to reject or criticize sharply

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