One of the most misused sets of homophones — words that sound alike but are spelled differently and have vastly different meanings — is the principal/principle pair. I recently read a notice about a new project that included a “principle” address as its location. I’ve seen organizations boast about their “guiding principals.” And I’ve seen leaders of professional service firms referenced as the firms’ “principles.” All those uses are wrong.
Principal ending in “pal” can be either a noun or an adjective. As a noun, it generally refers to an individual in a top-level position, such as the principal of a school, the principal of an accounting firm, or the principal who is a party in some sort of legal transaction. Way back when I was in school, the handy tool we were taught to remember the spelling was “the principal is my pal,” though the classmates who spent the most time with our principal definitely were not his pals.
As an adjective, “principal” has the same basic meaning as “first” or “primary.” The principal objective of our new budget was to bring expenses under control. The company’s principal reason for existing is to make money for its owners.
The other word, principle, generally refers to a tenet or basic truth upon which other activities depend, such as a moral foundation. As a noun, it’s most often used to reference a value, as in “the Declaration of Independence refers to the principles of life, liberty, and the pursuit of happiness” or “our company does business on the principle that the customer is always right.” When an individual is exemplary for following her moral compass, you may describe her as “principled.”
“The principal reason the principled principal disciplined the student was that he violated the school’s principles.”
Using the wrong version of that word pair may not seem to be a big deal, since they are pronounced identically, but it suggests to the reader that you’re not quite as bright as you really are. Accuracy counts.