principle

noun

1
(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
2
a basic truth or law or assumption
the principles of democracy
3
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
4
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
5
a rule or standard especially of good behavior
a man of principle
he will not violate his principles
6
rule of personal conduct

Also useful for “principle”:Unscrambler— Rearrange the letters in “principle”