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• principle
  principle

  noun

  an accepted or professed rule of action or conduct.
• Principle
  Principle

  noun

  Christian Science another word for God

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principle

American  

[prin-suh-puhl] / ˈprɪn sə pəl /

noun

• principles
  plural

1. an accepted or professed rule of action or conduct.

   a person of good moral principles.

2. a fundamental, primary, or general law or truth from which others are derived.

   the principles of modern physics.

   Synonyms:

   proposition, postulate, axiom, theorem

3. a fundamental doctrine or tenet; a distinctive ruling opinion.

   the principles of the Stoics.

4. principles, a personal or specific basis of conduct or management.

   to adhere to one's principles; a kindergarten run on modern principles.

5. guiding sense of the requirements and obligations of right conduct.

   a person of principle.

   Synonyms:

   honor, rectitude, probity, integrity

6. an adopted rule or method for application in action.

   a working principle for general use.

7. a rule or law exemplified in natural phenomena, the construction or operation of a machine, the working of a system, or the like.

   the principle of capillary attraction.

8. the method of formation, operation, or procedure exhibited in a given case.

   a community organized on the patriarchal principle.

9. a determining characteristic of something; essential quality.

10. an originating or actuating agency or force.

    growth is the principle of life.

11. an actuating agency in the mind or character, as an instinct, faculty, or natural tendency.

    the principles of human behavior.

12. Chemistry. a constituent of a substance, especially one giving to it some distinctive quality or effect.

13. Obsolete. beginning or commencement.

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idioms

1. in principle, in essence or substance; fundamentally.

   to accept a plan in principle.

2. on principle,

   1. according to personal rules for right conduct; as a matter of moral principle.

      He refused on principle to agree to the terms of the treaty.

   2. according to a fixed rule, method, or practice.

      He drank hot milk every night on principle.

principle ¹ British  

/ ˈprɪnsɪpəl /

noun

1. a standard or rule of personal conduct

   a man of principle

2. (often plural) a set of such moral rules

   he'd stoop to anything

   he has no principles

3. adherence to such a moral code; morality

   it's not the money but the principle of the thing

   torn between principle and expediency

4. a fundamental or general truth or law

   first principles

5. the essence of something

   the male principle

6. a source or fundamental cause; origin

   principle of life

7. a rule or law concerning a natural phenomenon or the behaviour of a system

   the principle of the conservation of mass

8. an underlying or guiding theory or belief

   the hereditary principle

   socialist principles

9. chem a constituent of a substance that gives the substance its characteristics and behaviour

   bitter principle

10. in theory or essence

11. because of or in demonstration of a principle

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Principle ² British  

/ ˈprɪnsɪpəl /

noun

1. Christian Science another word for God

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principle More Idioms  

1. see in principle; on principle.

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Usage

Principle and principal are often confused: the principal (not principle ) reason for his departure; the plan was approved in principle (not in principal )

Commonly Confused

See principal.

Synonym Usage

Principle, canon, rule imply something established as a standard or test, for measuring, regulating, or guiding conduct or practice. A principle is a general and fundamental truth that may be used in deciding conduct or choice: to adhere to principle. Canon, originally referring to an edict of the Church (a meaning that it still retains), is used of any principle, law, or critical standard that is officially approved, particularly in aesthetics and scholarship: canons of literary criticism. A rule, usually something adopted or enacted, is often the specific application of a principle: the golden rule.

Other Word Forms

Noun Inflected Forms

• principles
  plural

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Etymology

Origin of principle

First recorded in 1350–1400; Middle English, alteration of Middle French principe or Latin prīncipium, on the analogy of manciple; see principium

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Explanation

A principle is a kind of rule, belief, or idea that guides you. You can also say a good, ethical person has a lot of principles. In general, a principle is some kind of basic truth that helps you with your life. "Be fair" is a principle that guides (or should guide) most people and businesses. A politician who tries to do the right thing rather than win votes is acting on principle. A person who has principles is a good, decent person. On the other hand, if you say someone has no principles, that means they're dishonest, corrupt, or evil.

Example Sentences

See Examples For:

principle Principle principles

Mark Sanchez has reached an agreement in principle to end the civil case against him filed by a truck driver who got into a physical altercation with the former USC and NFL quarterback last fall.

From Los Angeles Times ● Oct. 14, 2026

For Stevens, the principle behind finding kit another home is simple.

From BBC ● Oct. 12, 2026

"The great advantage of the new nuclear clock in Vienna is that, if you use atomic nuclei rather than atoms, much higher precision is possible in principle," says Thorsten Schumm.

From Science Daily ● Oct. 11, 2026

But the incremental disappearance of ordinary interactions raises a question worth considering: What happens when convenience becomes the organizing principle of our public lives?

From Salon ● Oct. 11, 2026

The only way to clock the speed of a galaxy is by using the Doppler effect—the same principle used in state troopers’ radar guns.

From "Zero: The Biography of a Dangerous Idea" by Charles Seife

They are particularly concerned about weakening what is known as the Aboriginal Child Placement Principle - a framework designed to keep Indigenous children connected to family.

From BBC ● May 15, 2026

Ehrlich was often labeled a neo-Malthusian, a reference to the 18th-century British political economist Thomas Malthus, best known for “An Essay on the Principle of Population.”

From The Wall Street Journal ● Mar. 17, 2026

The Premack Principle is a motivational behavioral technique based on a reward system.

From Los Angeles Times ● Jan. 20, 2025

Thus a key Principle of our rule of law is that we must "respect, support, and defend the constitutional rights of all Americans" with fairness and due process of law.

From Salon ● Sep. 3, 2024

Maddie knew she could never repay Dympna; but now, according to the Aerodrome Drop-Off Principle, Maddie had a chance to pass the life-changing favors on.

From "Code Name Verity" by Elizabeth Wein

The end result is just a reflection of what he cares about, his morals and principles, while avoiding the unfunny thought of a comedian’s role in society, Rajapaksa said.

From Los Angeles Times ● Oct. 15, 2026

Russell Kirk and Friedrich Hayek held views that seem irreconcilable, but they both adhered more closely to fusionist principles than is commonly understood.

From The Wall Street Journal ● Oct. 11, 2026

Poppy's Promise is based on four care principles:

From BBC ● Oct. 8, 2026

"There will inevitably be greater scrutiny of how those same principles are applied closer to home."

From Barron's ● Oct. 8, 2026

Despite Abigail’s reservations, Adams wanted Gerry on the peace delegation to demonstrate his bipartisan principles and also to assure that he would receive candid reports from a trusted friend.

From "Founding Brothers: The Revolutionary Generation" by Joseph J. Ellis

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Related Words

• assumption
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• doctrine
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• proposition
• regulation
• rule
• truth

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