principle

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

Definition of principle

1a : a comprehensive and fundamental law, doctrine, or assumptionb (1) : a rule or code of conduct (2) : habitual devotion to right principles a man of principlec : 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 curiosityb : 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

See principle defined for English-language learners

See principle defined for kids

principle vs. principal

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.

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

Recent Examples of principle from the Web

The cause of the recusal flows self-evidently from basic legal principles.

— jonathan chait, Daily Intelligencer, "Donald Trump: L’état, C’est Moi," 20 July 2017
Giannelli Imbula is set to depart the bet365 Stadium after reaching an agreement in principle with Turkish giants Galatasaray over a potential loan move.

— SI.com, "Stoke City Midfielder to Complete Galatasaray Loan as Agreement Reached With Imbula," 19 July 2017
There is a competitive but collaborative atmosphere that embodies the core principles of Button.

— fortune editors, Fortune, "The 25 Best Small and Medium Workplaces in New York," 18 July 2017
But blowing off those principles can come at a high price.

— hannah seligson, Cosmopolitan, "Your Mobile Apps Are More Dangerous Than You Think," 15 July 2017
That’s not to say that using an organizing principle doesn’t help to give me a way to understand a patient.

— lori gottlieb, The Cut, "What Your Therapist Really Thinks: ‘Am I Normal?’," 14 July 2017
Her guiding principle is monotonicity—a relationship between variables in which, all else being equal, increasing one variable directly increases another, as with the square footage of a house and its price.

— paul voosen, Science | AAAS, "How AI detectives are cracking open the black box of deep learning," 6 July 2017
LIKE SO many relievers, Pat Neshek is a prisoner to his passions and his principles.

— marcus hayes, Philly.com, "Phillies all-star reliever Pat Neshek is strikingly quirky | Marcus Hayes," 6 July 2017
Those principles propelled Dave Gilboa and Neil Blumenthal into co-founding and running Warby Parker.

— susannah hutcheson, USA TODAY College, "How we became eyewear entrepreneurs: Neil Blumenthal and Dave Gilboa of Warby Parker," 30 June 2017

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.

Origin and Etymology of 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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First Known Use: 14th century

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PRINCIPLE Defined for English Language Learners

principle

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noun

Definition of principle for English Language Learners

: 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 Defined for Kids

principle

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noun prin·ci·ple \ˈprin-sə-pəl\

Definition of principle for Students

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

Medical Dictionary

principle

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noun 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