The noun principle has 6 senses (first 6 from tagged texts)
1. (14) principle, rule -- (a basic generalization that is accepted as true and that can be used as a basis for reasoning or conduct; "their principles of composition characterized all their works")
2. (9) principle -- (a rule or standard especially of good behavior; "a man of principle"; "he will not violate his principles")
3. (7) principle -- (a basic truth or law or assumption; "the principles of democracy")
4. (4) principle, rule -- (a rule or law concerning a natural phenomenon or the function of a complex system; "the principle of the conservation of mass"; "the principle of jet propulsion"; "the right-hand rule for inductive fields")
5. (2) principle, precept -- (rule of personal conduct)
6. (2) rationale, principle -- ((law) an explanation of the fundamental reasons (especially an explanation of the working of some device in terms of laws of nature); "the rationale for capital punishment"; "the principles of internal-combustion engines")