Dictionary

A fundamental assumption or guiding belief.

Example: We need some sort of principles to reason from.

A rule used to choose among solutions to a problem.

Example: The principle of least privilege holds that a process should only receive the permissions it needs.

(sometimes pluralized) Moral rule or aspect.

Example: I don't doubt your principles.

A rule or law of nature, or the basic idea on how the laws of nature are applied.

Example: Bernoulli's Principle

To equip with principles; to establish, or fix, in certain principles; to impress with any tenet or rule of conduct.