principle
- 01 B2 Upper Intermediate
a moral rule or belief that helps you know what is right and influences your behavior.
a fundamental truth or proposition that serves as the foundation for a system of belief or behavior or for a chain of reasoning.
Simple“She refused to lie about the accident because it went against her principles.”
In context“The senator maintained that sticking to his principles was more important than winning the upcoming election through compromise.”
PitfallHe is a man of high principals. He is a man of high principles.Do not confuse 'principle' (a rule or belief) with 'principal' (the head of a school or a main sum of money).
- 02 B2 Upper Intermediate
a basic law of nature or a rule that explains how a machine or system works.
a fundamental law, axiom, or doctrine of nature or science.
Simple“The pilot explained the basic principles of flight to the passengers.”
In context“Archimedes' principle explains why ships float by calculating the upward force exerted by the displaced water.”
- 03 B2 Upper Intermediate
a general idea or rule that is used as a base for other ideas.
a general scientific theorem or law that has numerous special applications across a field.
Simple“In principle, the plan sounds good, but we need to see the costs.”
In context“While the two parties agree on the proposal in principle, they remain divided on the specific details of implementation.”
- 04 C2 Proficiency
a basic substance in a plant or medicine that gives it a special quality.
a constituent of a substance, especially one giving it a particular quality or effect.
Simple“Scientists isolated the active principle in the leaf that helps reduce pain.”
In context“The laboratory succeeded in extracting the bitter principle from the root, allowing for more precise pharmaceutical testing.”
UsageOften used in chemistry or pharmacology to describe the 'active principle' of a drug.
Synonyms
principle vs principal — Principal is an adjective meaning main or a noun for a leader, while principle is always a noun meaning a fundamental rule or belief.
Usage principle applies · apply principle · ethical principle
“While Guardiola had principles he stuck to throughout his career, he did not stick to one system.”
“Bouke Klein Teeselink, an academic at King’s College London and an expert on the impact of AI on work, said the boot camp was a “good idea in principle”.”