principle

/ˈprɪnsəpl/ (bre, ipa) · /ˈprɪnsəpl/ (ame, ipa) · /ˈprin(t)-s(ə-)pəl -sə-bəl/ (ame, mw)

principle — noun

1. a general scientific or logical rule that explains how a system, process, or are

1.名詞C1
釋義

a general scientific or logical rule that explains how a system, process, or area of knowledge operates — for example, the principle of supply and demand in economics, or Archimedes' principle in physics

例句

The principle of supply and demand is central to modern economics.

principle of [field]: a core rule in a discipline

Archimedes' principle explains why some objects float in water.

同義詞
  • law

    a principle that is universally observed and often formulated mathematically (e.g., the law of gravity)

  • rule

    a more general term for a guideline; less fundamental than a scientific principle

  • tenet

    a principle held to be true by a group or organisation, especially in religion or politics

用法筆記

Often followed by "of" plus a field of knowledge, as in "the principle of supply and demand" or "principles of design."

常見錯誤

❌The principal of supply and demand drives prices.
✅The principle of supply and demand drives prices.
💡'principal' means the head of a school or most important; 'principle' means a rule or idea.

2. used to say that something is generally accepted as a good idea in theory, even

2.名詞C2
釋義

used to say that something is generally accepted as a good idea in theory, even if the practical details are not yet settled or fully carried out

例句

The committee agreed to the plan in principle but requested more details.

collocation: agree in principle

In principle, the proposal makes sense — the real difficulty is putting it into action.

contrast: in principle vs. putting into action

同義詞
  • theoretically

    more informal and broader in use; 'in principle' implies the general idea is accepted, whereas 'theoretically' leaves its acceptance open

  • in theory

    nearly interchangeable with 'in principle,' though 'in principle' often carries a stronger hint of agreement

反義詞
  • in practice

    the real-world application, as opposed to the general idea

文法句型

in principle

用法筆記

Used only as a fixed phrase — "in principle." Do not use "by principle" or "on principle" to mean the same thing. "On principle" belongs to sense 3 (see idiom "as a matter of principle").

常見錯誤

❌By principle, I support the idea.
✅In principle, I support the idea.
💡the fixed phrase is 'in principle,' not 'by principle.'

3. a firm personal belief about what is morally right or wrong that guides the way

3.名詞C2
釋義

a firm personal belief about what is morally right or wrong that guides the way you live and behave

例句

Obi refused to lie to the customer because it went against his principles.

idiom: go against one's principles

Devika left the company as a matter of principle after they fired a colleague unfairly.

idiom: as a matter of principle

同義詞
  • morals

    closely related; 'principles' are more consciously held and often publicly stated, whereas 'morals' can be internal and instinctive

  • values

    broader than principles; values include what you consider important in life, while principles are specific rules of right and wrong

  • ethics

    a formal system of moral principles, often in professional contexts (e.g., medical ethics)

用法筆記

Often uncountable when referring to someone's overall moral character (e.g., "a man of principle") and countable when referring to specific beliefs (e.g., "she has strong principles about honesty").

常見錯誤

❌I don't eat meat in principle of animals.
✅I don't eat meat as a matter of principle.' or 'I don't eat meat on principle.
💡'in principle of' is not a correct phrase.