n.
- a fundamental truth or proposition serving as the foundation for belief or action.
▸a rule or belief governing one's personal behaviour.
▸morally correct behaviour and attitudes:
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a man of principle.
- a general scientific theorem or natural law.
- a fundamental source or basis of something.
▸a fundamental quality or attribute.
- Chemistry an active or characteristic constituent of a substance.
Phrase
- in principle
in theory. - on principle
because of one's adherence to a particular belief.
Usage
Note that principle and principal do not have the same meaning. Principle is normally used as a noun meaning ‘a fundamental basis of a system of thought or belief’, as in this is one of the basic principles of democracy. Principal, on the other hand, is normally an adjective meaning ‘main or most important’, as in one of the country's principal cities. As a noun principal refers to the most senior or most important person in an organization: the deputy principal.
Etymology
ME: from OFr., from L. principium ‘source’, principia (pl.) ‘foundations’, from princeps, princip- ‘first, chief’.
