- principle of complementarity,
- principle of economy,
- principle of indifference,
- principle of least action,
- principle of mathematical induction
- 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.
- according to a fixed rule, method, or practice: He drank hot milk every night on principle.
Origin of principle
Word Origin for principle
late 14c., "origin, source, beginning; rule of conduct; axiom, basic assumption; elemental aspect of a craft or discipline," from Anglo-French principle, Old French principe "origin, cause, principle," from Latin principium (plural principia) "a beginning, commencement, origin, first part," in plural "foundation, elements," from princeps (see prince). Used absolutely for (good or moral) principle from 1650s.
It is often easier to fight for principles than to live up to them. [Adlai Stevenson, speech, New York City, Aug. 27, 1952]
Scientific sense of "general law of nature" is recorded from 1802. The English -l- apparently is by analogy of participle, etc.
Fundamentally, in general, but not necessarily in all particulars. For example, The diplomats accepted the idea in principle but would rely on experts to work out all the details. [Early 1800s]
see in principle; on principle.