Principal or Principle?

by Craig Shrives

What Is the Difference between "Principal" and "Principle"?

"Principal" and "principle" are easy to confuse because they sound identical (i.e., they are perfect homonyms). However, their meanings are very different.
  • "Principal" means main. For example:
    • It is my principal concern. correct tick
  • "Principal" is the head of an institution (especially a school). For example:
    • Go and stand outside the principal's office! correct tick
  • "Principle" is a general law or a code of conduct. For example:
    • Apply the guiding principle at all times. correct tick
principal or principle?

More about "Principal" and "Principle"


"Principal" is usually an adjective meaning "main" or "key." For example:
  • The principal objective is to make a profit. correct tick
  • The inspector highlighted my principal concern in his opening sentence. correct tick
"Principal" can also be a noun meaning "head" or "chief." It is commonly used to mean "head teacher." For example:
  • Here comes the principal.correct tick
  • (principal = head teacher)
  • The allegations against the former principal were that he not only allowed the cage fights to take place, but he also encouraged the participants. correct tick

Principal and Money

When referring to a loan, the "principal" (or "principal sum") is the original amount of a debt or investment on which interest is calculated. For example:
  • With an interest-only mortgage, the principal sum is repaid at the end. correct tick


"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." For example:
  • That is a great idea in principle. correct tick
  • He applied the Aufbau principle to determine the electron configuration of the silicon. correct tick
"Principle" often appears in the plural form "principles":
  • No! It is against my principles! correct tick
  • Those are my principles. If you don't like them, I have others. correct tick (Comedian Groucho Marx)
  • You could strengthen your argument by appealing to more general principles. correct tick

Common Terms with Principal and Principle

Here are some common terms with "principal":
  • principal agent
  • principal amount
  • principal contractor
  • principal designer
  • principal dancer
  • principal focus
  • principal investor
Here are some common terms with "principle":
  • Archimedes principle
  • ethical principle
  • first principle
  • fundamental principle
  • guiding principle
  • proximity principle

A Video Summary

Here is a video summarizing this lesson on "principal" and "principle":

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