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HomeWhich One?SpellingPrincipal vs Principle
ESEN
Which one to use?Intermediatenoun / adjectivenoun

PrincipalvsPrinciple

One is a school head or the most important thing; the other is a rule or moral belief.

Side-by-side comparison

Principal
noun / adjective

"Principal" as a noun is the head of a school or the most important person in something. As an adjective it means main or most important. "The principal reason" = the main reason.

  • The school principal called a meeting with all teachers.

  • Our principal concern is the safety of the staff.

  • She was the principal investor in the project.

Principle
noun

"Principle" is a fundamental rule, belief, or moral value that guides behaviour. "Act on principle" = act according to your values. "A matter of principle" = an issue of ethics.

  • He refused to sign the contract on principle.

  • The principle of equality is at the core of the law.

  • Never compromise your principles for short-term gain.

Common mistake

  • •"The school principle" when meaning the head teacher is wrong (correct: principal).
  • •And "a man of high principals" when meaning moral values is wrong (correct: principles).

Trick to remember it

  • •The school "principal" is your pal, the word ends in PAL.
  • •A "principle" ends in LE, like the word "rule."

Quick rule

  • •"Principal" = most important person or thing, ends in AL.
  • •"Principle" = rule or moral value, ends in LE.

Did you know?

In finance and investment, PRINCIPAL has a precise technical meaning: the original capital of a loan, mortgage, or investment, as distinct from INTEREST. When you pay a mortgage, part of each payment reduces the PRINCIPAL (the capital you owe) and another part pays the period's INTEREST. The amortization of a long-term mortgage is mostly interest in the early years and more principal toward the end. That is why the first years of a mortgage "barely reduce the debt", because most of the payment goes to interest, not principal.

Practise what you learned

Exercise 1 · Pick the right one

The _____ of the school called an emergency meeting for all teachers.

Exercise 2 · Pick the right one

She refused to cheat as a matter of _____ . She believes in being honest.

Exercise 3 · Form the word

Complete: "The _____ reason she left was the long commute." (principal / principle)

Related word pairs

AcceptvsExcept

One means to receive or agree to something, the other means to exclude or not include.

AdvicevsAdvise

'Advice' is the guidance you receive (noun); 'advise' is the act of giving that guidance (verb).

AffectvsEffect

'Affect' is the verb meaning to influence something; 'effect' is the noun meaning result or consequence.

AislevsIsle

'Aisle' is the walkway between rows of seats or shelves; 'isle' is a small island.

BL

Bryan López

Founder of SpeakUP Academy

July 22, 2026

See all Spelling pairsExplore English suffixes
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