principle
noun
prin·ci·ple
ˈprin(t)-s(ə-)pəl
-sə-bəl
1
a
: a comprehensive and fundamental law, doctrine, or assumption
well-established economic principles
b(1)
: a rule or code of conduct
Plagiarism is against the school's principles.
… a new series of laws declared a fourth principle: the colonies could not make or export items that competed with English products …—Mary Beth Norton et al.
(2)
: habitual devotion to what is right
a leader of principle
As a matter of principle, he would not accept the gift.
The photographer refused on principle to sell photos to the tabloids.
c
: the laws or facts of nature underlying the working of an artificial device
the principle of the internal-combustion engine
Note: Do not confuse this word, principle, with the similar principal. As a noun, principal has various meanings referring to someone with controlling authority ("the school principal") or in a leading position ("the ballet's two principals"), as well as meanings relating to finance, law, and architecture. As an adjective, principal typically means "most important" ("the principal reason").
2
: a primary source : origin
The principle of his great success lay in the fact of his appearance at a critical epoch.—The North American Review
3
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see also:
Cite this Entry
“Principle.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/principle. Accessed 1 Sep. 2026.
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