principal vs. principle

What is the difference between principal and principle?

This pair of words often causes trouble for English learners and native speakers alike, since they’re both pronounced /ˈprɪnsɪpəl/.
Principal is both a noun and an adjective. As a noun, it most generally means “a person who holds a position of primary importance in or leads some event, action, or organization,” most commonly referring to the head of an elementary, middle, or high school. As an adjective, principal means “chief, foremost, or primary; first in importance, value, rank, etc.” For example:
  • “The principal made an announcement to the school about the recent policy changes.”
  • “The principal actor in the play quit a week before the premiere.”
  • “Our principal interest is in maintaining steady growth over the first four quarters of the company’s existence.”
Principle can only function as a noun, generally meaning “an established, accepted, or fundamental rule, law, axiom, or doctrine,” or “a personal set of moral standards, rules, or beliefs.” For example:
  • “It’s not about the money; it’s about the principle of sticking by your friends, no matter what!”
  • “Can you explain the principle of the conservation of energy?”
  • “A savvy businesswoman, she never deviates from her principles when striking a deal.”

Spelling Tricks and Tips

Fortunately, there are a couple mnemonic tricks we can use to remember which spelling is correct:
  • If what you’re writing is an adjective, then the word will always be principal.
  • If you’re referring to a person, use principal, because a person can be your pal.
  • A principle is a concept that can be taught to someone’s disciple.
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