1 [C,U] a rule for good behaviour, based on what a person believes is right 原则；行为准则: He doesn't eat meat on principle. 他依照原则不吃肉。She refuses to wear fur. It's a matter of principle with her. 她拒绝穿毛皮，对她来说，那是个原则问题。

2 [C] a basic general law, rule or idea 原理；定律: The system works on the principle that heat rises. 那系统根据热空气上升的原理运作。The course teaches the basic principles of car maintenance. 这门课程教授汽车保养的基本原理。