principle

noun
prin·​ci·​ple | \ ˈprin(t)-s(ə-)pəl How to pronounce principle (audio) , -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

PCWorld sat down with Josh Newman, the general manager of mobile innovation segments for Intel, for an exclusive look at Project Athena’s guiding principles. Brad Chacos, PCWorld, "6 important CES 2019 reveals and trends that PC enthusiasts need to know about," 11 Jan. 2019 This type of research was initially developed in the 1980s at MIT by roboticist Rodney Brooks, who developed a number of robots based on their principle. Avery Thompson, Popular Mechanics, "DARPA Wants to Turn Insect Brains into Robot Brains," 10 Jan. 2019 On our retreat, a five-night, small-group experience in the wildlife refuge of Kenya’s Laikipia Plateau, the idea was to apply these same principles to human nature. Pilar Guzmán, Condé Nast Traveler, "Editor's Letter: The Wisdom of the Wild," 10 Oct. 2018 There are encouraging signs that the Conservative Party is relearning its conservative principles. The Economist, "The Conservative Party has trashed the basic principles of conservatism," 12 July 2018 The spirit suggested the party’s name and laid out its founding principles. Julia Wallace, New York Times, "‘Fireflies’ and ‘Ghosts’ in Cambodia Prop Up Facade of Real Election," 11 July 2018 Although the program is currently only used in the lower grades, its principles have stuck with the older students. Mari A. Schaefer, Philly.com, "Students use 'feedback' to build community, solve problems," 15 June 2018 Rational treatment is based upon an understanding of the basic principles of body unity, self-regulation, and the interrelationship of structure and function. Carolyn L. Todd, SELF, "What Is a Doctor of Osteopathic Medicine, and Should You See One?," 6 Feb. 2019 As firefighters, one of the core principles we’re taught is to solve the problem at hand while causing the least collateral damage possible. Andrew Northshield, Popular Mechanics, "How To Get Keys Out of a Locked Car," 19 Dec. 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

8 Apr 2019

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Time Traveler for principle

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

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More Definitions for principle

principle

noun

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

principle

noun
prin·​ci·​ple | \ ˈprin-sə-pəl How to pronounce principle (audio) \

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

principle

noun
prin·​ci·​ple | \ ˈprin(t)-sə-pəl How to pronounce principle (audio) \

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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More from Merriam-Webster on principle

Rhyming Dictionary: Words that rhyme with principle

Spanish Central: Translation of principle

Nglish: Translation of principle for Spanish Speakers

Britannica English: Translation of principle for Arabic Speakers

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