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.Scientific sense of "general law of nature" is recorded from 1802. The English -l- apparently is by analogy of participle, etc.