(cryptography) The idea that a cryptosystem should be designed to be secure even if everything about the system, except the secret key, is public knowledge.

(philosophy, rhetoric) The principle according to which an argument should be evaluated in light of its best, strongest possible interpretation.

(sociolinguistics) The idea that listeners and speakers need to cooperate in order to communicate effectively.

(geometry) A development of the method of indivisibles, dealing with two-dimensional area or three-dimensional volume based on the intersections of lines or planes surrounding a region. It was an early step toward integral calculus.

(fluid dynamics) A law that states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially, is equal to the weight of the fluid that the body displaces.

(physics) the principle that classical physics is the limit of quantum physics as quantum numbers approach infinity

plural of superposition principle

Alternative form of non-aggression principle

(linguistics) The idea of using ideograms as phonograms representing the sounds of the words expressed by the original ideograms.

(UK, education) The idea that university places should be available to everybody who qualifies for them by ability and attainment.