principle

Etymology

From Middle English principle, from Old French principe, from Latin prīncipium (“beginning, foundation”), from prīnceps (“first”), surface etymology is from prīmus (“first”) + -ceps (“catcher”); the former ultimately from Proto-Indo-European *preh₂- (“before”); see also prince.

noun

1. A fundamental assumption or guiding belief.
   We need some sort of principles to reason from.
   Let us consider ‘my dog is asleep on the floor’ again. Frege thinks that this sentence can be analyzed in various different ways. Instead of treating it as expressing the application of __ is asleep on the floor to my dog, we can think of it as expressing the application of the concept my dog is asleep on __ to the object the floor (see Frege 1919). Frege recognizes what is now a commonplace in the logical analysis of natural language. We can attribute more than one logical form to a single sentence. Let us call this the principle of multiple analyses. Frege does not claim that the principle always holds, but as we shall see, modern type theory does claim this. 2011-07-20, Edwin Mares, “Propositional Functions”, in The Stanford Encyclopedia of Philosophy, retrieved 2012-07-15
2. A rule used to choose among solutions to a problem.
   The principle of least privilege holds that a process should only receive the permissions it needs.
3. (sometimes pluralized) Moral rule or aspect.
   I don't doubt your principles.
   You are clearly a person of principle.
   It's the principle of the thing; I won't do business with someone I can't trust.
4. (physics) A rule or law of nature, or the basic idea on how the laws of nature are applied.
   [[Bernouilli's Principle Bernoulli's Principle
   The Pauli Exclusion Principle prevents two fermions from occupying the same state.
   The principle of the internal combustion engine
   Some poems, echoing the purpose of early poetic treatises on scientific principles, attempt to elucidate the mathematical concepts that underlie prime numbers. Others play with primes’ cultural associations. Still others derive their structure from mathematical patterns involving primes. 2013 July-August, Sarah Glaz, “Ode to Prime Numbers”, in American Scientist, volume 101, number 4
5. A fundamental essence, particularly one producing a given quality.
   Many believe that life is the result of some vital principle.
   Cathartine is the bitter, purgative principle of senna. 1845, William Gregory, Outlines of Chemistry
6. A source, or origin; that from which anything proceeds; fundamental substance or energy; primordial substance; ultimate element, or cause.
7. An original faculty or endowment.
   those active principles whose direct and ultimate object is the communication either of enjoyment or suffering 1828, Dugald Stewart, The Philosophy of the Active and Moral Powers of Man
8. Misspelling of principal.
9. (obsolete) A beginning.

verb

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