principle

Universal Words noun 1 [C,usually pl.,U] a moral rule or a strong belief that influences your actions: He has high moral principles. * I refuse to lie about it; it's against my principles. * Stick to your principles and tell him you won't do it. * She refuses to allow her family to help her as a matter of principle. * He doesn't invest in the arms industry on principle. 2 [C] a law, a rule or a theory that sth is based on: the principles and practice of writing reports * The principle behind it is very simple. * There are three fundamental principles of teamwork. * Discussing all these details will get us nowhere; we must get back to first principles (= the most basic rules). 3 [C] a belief that is accepted as a reason for acting or thinking in a particular way: the principle that free education should be available for all children 4 [sing.] a general or scientific law that explains how sth works or why sth happens: the principle that heat rises * A tidal current turbine is similar in principle to a windmill. IDIOMS in principle 1 if something can be done in principle, there is no good reason why it should not be done although it has not yet been done and there may be some difficulties: In principle there is nothing that a human can do that a machine might not be able to do one day. 2 in general but not in detail: They have agreed to the proposal in principle but we still have to negotiate the terms.