principle

noun

prin·​ci·​ple ˈprin(t)-s(ə-)pəl 

-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

Synonyms

• ABC(s)
• alphabet
• basics
• elements
• essentials
• fundamentals
• grammar
• rudiments

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

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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

Phrases Containing principle

• a matter of principle
• acceleration principle
• exclusion principle
• anthropic principle
• pleasure principle
• Heisenberg uncertainty principle
• indeterminacy principle
• on principle
• uncertainty principle
• weak anthropic principle
• Pauli exclusion principle
• strong anthropic principle
• Bernoulli's principle
• Hardy-Weinberg principle
• in principle
• as a matter of principle

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• a matter of principle
• acceleration principle
• exclusion principle
• anthropic principle
• pleasure principle
• Heisenberg uncertainty principle
• indeterminacy principle
• on principle
• uncertainty principle
• weak anthropic principle
• Pauli exclusion principle
• strong anthropic principle
• Bernoulli's principle
• Hardy-Weinberg principle
• in principle
• as a matter of principle

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Kids Definition

principle

noun

prin·​ci·​ple ˈprin(t)-s(ə-)pəl 

-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 

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