Halloween is next week, and thousands of people are “scarifying” their houses in anticipation of the hordes of trick-or-treating children. Why people have taken to decorating houses as if it were Christmas is a subject for a column on marketing, not language, so we’ll dispense with that.

Instead, we’ll focus on words appropriate to the season.

“Scarify,” the first syllable rhyming with “stair,” means “to make scary.” Its root, of course, is “scare.” But another word is spelled the same with a different meaning: With the first syllable rhyming with “star,” it means “to make small incisions in the skin.”

The two words have few ancestors in common. While some usage authorities disdain the use of the “scary” one, it’s perfectly legitimate. It was first used in 1794, according to The Oxford English Dictionary ; Merriam-Webster traces it to 1785. “Scare” is related to “shy,” as in a horse that “shies” from danger.

The disfiguring “scarify” comes, of course, from “scar,” which has as one of its close cousins the word “scribe.” (Those small incisions are like writing on the skin.) The OED traces the first use of that back to 1541.

Not many people are employing “scarify” when they invite kids to their seasonalized haunted houses, and even the other “scarify” is limited mostly to medical journals and the occasional gardening magazine. (Seeds are “scarified” to encourage them to sprout.) It’s a fun word, but when it’s in print, the context needs to make clear which one is meant, or people might think you’re interested in “scarring” kids for life. (Come to think of it, “scaring” can do that too.)

Many kids will join in the spirit by carving pumpkins, or, in these overcautious days, painting them or putting stickers on them. They’re making “jack-o’-lanterns.” That’s the spelling preferred by dictionaries. Many publications, though, call them “jacko’ lanterns” or “jacko lanterns.” Sorry, it has nothing to do with Michael Jackson: “Jack-o’-lantern” means, literally, a man with a lantern or, figuratively, a “will-o’-the-wisp,” an elusive goal or target, usually one that is a bit deceiving.

That deception is key to the reason the “jack-o’-lantern” is a Halloween symbol. In the Old World, where the mists rising from the moors could play tricks with the eyes, many people believed that evil spirits roamed with illusory flickering lanterns, to lure unsuspecting people into the mire. What better night for a “jack-o’-lantern” to roam than on Halloween, when the dead are said to be able to walk the earth?

Indeed, another word for “will-o’-the-wisp” is “ignis fatuus,” derived from the Latin for “foolish light” and defined as “a phosphorescent light that hovers or flits over swampy ground at night, possibly caused by spontaneous combustion of gases emitted by rotting organic matter.”

So carry a “jack-o’-lantern” as you wander the moors on All Hallows’ Eve, lest the “ignis fatuus” “scarify” you.

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Merrill Perlman managed copy desks across the newsroom at The New York Times, where she worked for 25 years. Follow her on Twitter at @meperl.