Definition of principle in English:

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Pronunciation: /ˈprinsəpəl/


1A fundamental truth or proposition that serves as the foundation for a system of belief or behavior or for a chain of reasoning: the basic principles of Christianity
More example sentences
  • And yet, of course, our principles of fairness and justice must be upheld.
  • Although its application was inevitably uneven, the Code Napoléon was intended to serve as a universal set of principles founded on reason.
  • Following the enlightenment principle of truth through reason alone, it was thought that history cannot be determined until theology has been removed.
truth, proposition, concept, idea, theory, assumption, fundamental, essential, ground rule
1.1 (usually principles) A rule or belief governing one’s personal behavior: struggling to be true to their own principles she resigned over a matter of principle
More example sentences
  • If you can forsake your fundamental principles for any reason then you are not the kind of person who can take the country forward.
  • Rarely have I encountered anyone as passionate and determined in his principles as Donald Bruce, a true patriot and a man who led a remarkable life.
  • There are three key defining experiences in my life that form the foundation of my principles and beliefs.
1.2Morally correct behavior and attitudes: a man of principle
More example sentences
  • It seems that in situations such as this, politics become incompatible with conscience, principle, decency and self-respect.
  • How in one walk of life a person can have such a rigid sense of right and wrong - and in another he can operate with a total disregard for principle, integrity and fair play.
  • But he's clearly a man of principle and unbending honesty - who, at times, can be cruelly insensitive, as when he tells a man he has casually examined that he has a tumour.
1.3A general scientific theorem or law that has numerous special applications across a wide field.
Example sentences
  • Physics has a big advantage here, since the ability to derive interesting conclusions from general principles comes earlier in physics than in other sciences.
  • Guitar pickups work by the principles of magnetic induction.
  • One line of evidence for the holographic principle comes from black hole physics.
1.4A natural law forming the basis for the construction or working of a machine: these machines all operate on the same general principle
More example sentences
  • Yet, that was the age of levers and pulleys, and machines based on mechanical principles were being used as analog computers in many different ways.
  • The principles underlying steam power, machine tools, and mass production were less familiar, hence less transparent.
  • However, back then, explanations that were given to the general public regarding the actual principle of the flying machine appeared to be quite vague.
2A fundamental source or basis of something: the first principle of all things was water
2.1A fundamental quality or attribute determining the nature of something; an essence: the combination of male and female principles
More example sentences
  • Just as the male and female principles complement each other, our views of history also much combine to give a holistic view of the past.
  • As sun and moon represent the male and female principles, once again we see the potential for a happy union between you.
  • Holding the rapt attention of the audience, the duo exemplified the concept of the male and female principles working in harmony and balance in the Universe, unique to Hindu mythology.
2.2 [with adjective] Chemistry An active or characteristic constituent of a substance, obtained by simple analysis or separation: the active principle in the medulla is epinephrine
More example sentences
  • Various studies on the active principles of the manchineel tree have shown tigliane phorbol esters to be the likely cause of the severe reactions.
  • The pungency of pepper is due to the active principles it contains - the volatile oil, piperine, and resin.
  • The active principles were identified as baicalein from the first and methyl gallate from the last two plants.


On the confusion of principle and principal, see principal (usage).



in principle

As a general idea or plan, although the details are not yet established or clear: the government agreed in principle to a peace plan that included a ceasefire
More example sentences
  • The plan was accepted in principle but the details for it were not.
  • Councillors agreed to the scheme in principle, with the detail being delegated to planning officers.
  • The town council says it supports the plan in principle, but says there could be problems finding a suitable location.
1.1Used to indicate that although something is theoretically possible, it may not actually happen: in principle, the banks are entitled to withdraw these loans when necessary
More example sentences
  • The first test here should be whether infinite computing power is, in principle, even possible.
  • Although having a smoke free environment seems good in principle, how would it be enforced?
  • However, he sees no reason to believe that a machine cannot, in principle, do the things humans can do.

on principle

Because of or in order to demonstrate one’s adherence to a particular belief: he refused, on principle, to pay the fine
More example sentences
  • I have never been in a limo in my life and would refuse to do so on principle.
  • Pittman said he later spoke to an employee who apologized and asked him to keep his subscription, but he quit on principle.
  • But I wouldn't go in there now on principle, even if you paid me.


Late Middle English: from Old French, from Latin principium 'source', principia (plural) 'foundations', from princeps, princip- 'first, chief'.

Words that rhyme with principle


For editors and proofreaders

Syllabification: prin·ci·ple

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