principal and principle - the difference

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Principal means main.
A principal is the head (of a department).
Principle means general law or code of conduct.

Writers occasionally confuse the words principal and principle.


In its most common role, principal is an adjective meaning main or key.

  • The principal objective is to make a profit.
  • (The adjective principal modifies the noun objective.)
    (principal = main or key)
  • The inspector highlighted my principal concern in his opening sentence.
  • (principal = main or key)

The word principal can also be noun mean head or chief. It is commonly used to denote head teacher in the US.
  • Here comes the principal. 
  • (principal = head teacher)
  • The allegations against the former principal were that he not only allowed the cage fights to take place, but he also he egged on the participants.


The word principle is a noun. It has a range of meanings, including rule, belief, tenet and theory.  In general, principle offers the idea of general law or code of conduct.
  • No! It is against my principles!
  • That is a great idea in principle.
  • Those are my principles. If you don't like them, I have others. (Groucho Marx quote)
  • You could strengthen your argument by appealing to more general
  • He applied the Aufbau principal to determine the electron configuration of the silicon.
  • (should be principle / principle = theory or general law)
Select the correct version:



If you imagine that the l on the end of principal looks like a 1, then the last two letters become A1.  This may help you to remember that principal denotes the most important or main.
  • My principal concern is the safety of the dove.
  • (my A1 concern, i.e., main concern)
  • You can explain your absence to the principal.
  • (to the A1, i.e., the most important person in the department)

When referring to a loan, the principal (or principal sum) is the original amount of a debt or investment on which interest is calculated.

What are nouns? What are verbs? List of easily confused words
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