principle

noun

prin·​ci·​ple ˈprin(t)-s(ə-)pəl How to pronounce principle (audio)
-sə-bəl
1
a
: 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
3
a
: 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
Principle vs. Principal: Usage Guide

Evidence of confusion between principle and principal can be found even in publications overseen by professional editors. To keep these words straight, remember that principle functions only as a noun, and in its most common uses refers to a basic rule or law, as in

a guiding principle

or

a matter of principle.

If you are looking for an adjective form of this word, you must use principled, as in

taking a principled stand.

Principal functions as both a noun and an adjective. The noun has various meanings referring to someone with controlling authority

the school principal

or in a leading position

the ballet's two principals

, but also has meanings relating to finance, law, and architecture. As an adjective, principal typically means "most important," as in

the principal reason.

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

Example Sentences

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 on the Web The findings by the team in Beijing underscore a core principle in ecology: that an imbalance at one level of the food chain can cascade to throw all the others off. Meaghan Tobin, Washington Post, 3 Feb. 2023 Negotiations between Democratic and Republican senators collapsed over a range of issues, including qualified immunity, a legal principle that generally shields police from personal liability. Los Angeles Times, 1 Feb. 2023 Doue, who modeled for Grès, looked like a fashion illustration come to life, which seems especially on point as the upcoming Karl Lagerfeld exhibition at the Costume Institute uses the designer’s drawings as an organizing principle. Laird Borrelli-persson, Vogue, 30 Jan. 2023 The new litigation turns on a longstanding principle that federal law, including FDA decisions, pre-empt state laws. Matthew Perrone, Fortune, 26 Jan. 2023 Based on a visual concept that dates back to the Ancient Greeks, the Golden Ratio, or the divine proportion, is a mathematical principle usually applied to art and architecture. Lindy Segal, Harper's BAZAAR, 26 Jan. 2023 The new litigation turns on a longstanding principle that federal law, including FDA decisions, pre-empt state laws. Matthew Perrone, ajc, 25 Jan. 2023 The litigation turns on a longstanding legal principle that federal law, including FDA decisions, pre-empt state laws. CBS News, 25 Jan. 2023 That’s a legal principle that basically says courts cannot opine on internal workings, including disciplinary issues, of religious institutions. Cory Shaffer, cleveland, 19 Jan. 2023 See More

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.

Word History

Etymology

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

First Known Use

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

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

Dictionary Entries Near principle

Cite this Entry

“Principle.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/principle. Accessed 6 Feb. 2023.

Kids Definition

principle

noun
prin·​ci·​ple ˈprin(t)-s(ə-)pəl How to pronounce principle (audio)
-sə-bəl
1
: a general or basic truth on which other truths or theories can be based
scientific principles
2
: a rule of conduct
a person of high principles
3
: a law or fact of nature which makes possible the working of a machine or device
the principle of magnetism
the principle of the lever

Medical Definition

principle

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