There's more to it than “the principal is your pal.”
As a noun, the word “principal” has more than ten meanings. As we’ve already seen, it refers to the head of a school. It also refers to the non-interest portion of a loan, as in “The principal is $250,000.” I don’t want to read the dictionary to you, so feel free to look up all the meanings.
We’ll just jump to the meaning that might answer Sarah’s question. One of the meanings of “principal” is a person in a leading or starring role. This could refer to a person acting in a play or movie, as in “Chris Pine and Zachary Quinto are the principals in the movie ‘Star Trek.’” I believe we can make this definition fit the business definition Sarah is looking for.
A dictionary of business terms (3) states that a principal is “a high-level individual (i.e., partner) in a CPA firm having major authority and responsibilities” or “an owner, especially one with executive authority, of a business firm.” Now, Sarah is working for a computer company, not a CPA firm, but no matter. You can indeed refer to someone as a principal of a business. Those who are the heads of large corporations are called CEOs, but if you own a small graphic design firm, for example, or are a bigwig in a computer firm, you can call yourself a principal.
In summary, please remember that “principle” and “principal” are both pronounced “principle.” I've just said them differently here to make it easier to follow along. Although they sound alike they're spelled differently and have different meanings.
“Principle” with a “p-l-e” has one main meaning: a rule or doctrine. “Principal” with a “p-a-l,” on the other hand, has many meanings, including the leader of a school, the non-interest part of a loan, and an important person in a business. Your principal is indeed your pal, but an important person in a business can be your pal, too.
The Curious Case of the Misplaced Modifier
This podcast was written by Bonnie Trenga, author of The Curious Case of the Misplaced Modifier, who blogs at sentencesleuth.blogspot.com, and Mignon Fogarty, Grammar Girl, is the author of the paperback book Grammar Girl's Quick and Dirty Tips for Better Writing.