[n] 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"
[n] a basic truth or law or assumption; "the principles of democracy"
[n] 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"
[n] 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"
[n] a rule or standard especially of good behavior; "a man of principle"; "he will not violate his principles"
[n] rule of personal conduct