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.
principle prin·ci·ple (prĭn'sə-pəl)
A basic truth, law, or assumption.
A rule or law concerning the functioning of natural phenomena or mechanical processes.
One of the elements composing a chemical compound, especially one that gives some special quality or effect.
The essential ingredient in a drug.