Definition of principle
- a man of principle
- prepared to accept the proposition in principle
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
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.
Yes, these two words are confusing; we see evidence of the misuse of both in newspapers and books which have been overseen by professional editors, so don’t feel bad if you have trouble with them. Principle only functions as a noun (such as “a comprehensive and fundamental law, doctrine, or assumption”); if you want it to be an adjective you must use the word principled. Principal, on the other hand, may function as a noun (such as the head of a school) or as an adjective (meaning “most important”).
: 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
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