Don’t confuse “principle” and “principal”.
“Principle” is a noun. It means a basic rule or assumption: He struggled to learn the principles of geometry. “Principal” can be a noun or an adjective. As a noun, it usually means the leader of a school or business: The principal gave me detention. The executives wrote a report for the principals. As an adjective, it means most important: Lester has the principal role in the play.
Here’s a memory shortcut for you. Remember this phrase: “The principal is your pal.” That takes care of the noun version of the word. As for the rest…..well, once again, the “a” in “principal” stands for “adjective.”
