Gerrit Petersen, of Brookline, Mass., writes: “With increasing frequency, I’ve been hearing the phrase to step foot in substituted for the common idiom to set foot in, primarily on television. The phrase troubles me every time I hear it. Please step in and set me, or someone, straight.”

It’s true that set foot in is far and away the more common phrase. And thirteen citations that include set foot in are scattered around the Oxford English Dictionary, the earliest of which (illustrating the use of the now obsolete and rare word reguerdonment, meaning “reward”) is from 1599. But the version you don’t like, step foot in, is also in the OED, with citations dating back to 1540. According to a note under step, it’s now seen and heard only in the United States.

The question remains whether we ought to consider it a mistake. Citations in the OED include, without demur, many words and phrases widely regarded as incorrect—for instance, baited breath, free reign, hone in, and all ready meaning “already.” Some of these are very old and appear in sentences that modern readers would consider rife (which is not to say ripe) with mistakes. For instance, from a 1533 book by John Frith: “When we say that such a man hath delyuered his freende from the gallowes, we mean not that he was all ready hanged.” Others are modern. For instance, from a 2002 magazine article: “Balanchine’s classes were famous for honing in on the basics.” Ouch.

Language geeks have given the name eggcorns to usages of this kind—“spontaneous reshapings of known expressions” which seem to make sense. (Eggcorn is itself an eggcorn, for acorn.) Whether step foot in is, or originally was, an eggcorn has been hotly but inconclusively debated. However, no one argues that set foot in is anything other than standard English. So step foot in is one of those phrases that we’re probably better off not using even though there’s little reason to object if others use them.

Suzanne Staszak-Silva, of Scotch Plains, N.J., writes: “My husband and I have a dispute regarding the use of the term landline. When people receive or make calls on a cellular phone but decide they would like to take the call on a phone connected to the wall via a phone jack, they usually refer to this phone as a landline. My husband says this is incorrect and the right term is LAN (local-area network) line. I say he’s wrong. I think people use landline to denote a phone that is connected to the large brown poles that line our streets, and that LAN line refers to computer connections. Who is correct?”

You are. Anyone who doesn’t want to call a phone line a phone line ought to call it a WAN (wide-area network) line. And thanks for the new eggcorn.

William D. Sharpe, of Springfield, Mo., writes: “Recently an acquaintance referred to his high-school alma mater as a magnate school. I jokingly asked if his school was named after J. P. Morgan, and said that I was under the impression that such schools were, in fact, referred to as magnet schools, the implication being that they attract bright students. He was quite insistent that his school was known as a magnate school. He claimed the name referred to such schools’ usual mission of concentrating on a particular area of study and turning out students who had expertise in that area—that is, magnates. Your opinion?”

Another eggcorn! As you know, magnate doesn’t just mean “an expert”; it means “a powerful or influential person, especially in business or industry,” as The American Heritage Dictionary defines the word. Top-ranked graduate schools of business might qualify as magnate schools, but that’s about it.

To see hundreds of other eggcorns, visit the Eggcorn Database, at www.eggcorns.lascribe.net. As of this writing, magnate for magnet isn’t listed there, though the opposite error is (together with some commentary about whether this is really an eggcorn or just a spelling mistake). An example in the database, culled from Details magazine, is “I was … reading over an American woman’s shoulder as she e-mailed a friend about her plans for the rest of July: ‘I’m going to find a shipping magnet and marry him!’”

Do you have a language dispute? Write to Word Court in care of The Atlantic Monthly, P.O. Box 67375, Chestnut Hill, MA 02467, or send e-mail to msgrammar@theatlantic.com. All letters become the property of Word Court. Ms. Grammar is also on the Web, at www.theatlantic.com/courtrecord.