A Word, Please: Apostrophes can be tricky, but most follow simple rules

He walks softly and carries a big stick. He uses it to make marks that look like little sticks. He prowls the streets at night, terrorizing shopkeepers and sign makers alike.

But I’m betting regular readers of this column will like him.

The town of Bristol in the United Kingdom has its very own apostrophe vigilante. He goes around at night with a wooden stick, his “Apostrophiser,” and uses it to apply stickers to poorly punctuated signs.

In some cases, the stickers cover up erroneous apostrophes, such as the one in a manicurist sign advertising that they do “nail’s.” Other times, he applies a needed apostrophe to signs advertising “gentlemens outfitters.”

The BBC recently published a video of Bristol’s punctuation vigilante in action, his blurred-out face adding to the intrigue. No one’s caught him so far, and he’s been at it for 13 years.

I have a lot of sympathy for people who struggle with apostrophes. They’re hard. But my sympathy wanes a bit when it comes to businesses whose whole job is to print signs. I mean, come on, folks. Unlike emails and tweets, signs are made to endure as long as possible while attracting as many eyeballs as possible.

And sign makers, it’s, you know, your job. Dust off an old schoolbook. Ring up a word-nerd friend. Make an effort. Here’s a bit of help.

The hardest thing about apostrophes is that they have two jobs: They show possession, as in Bob’s hat, and they form contractions, as in “I can’t hear you.” Occasionally, they even form plurals, as in “We caught some z’s.”

For possessives and some contractions, apostrophes work with the letter S: Bob’s hat. Bob’s here.

Note how the apostrophe-plus-S combo has different functions in our Bob examples. In the first, it makes the possessive of Bob. It the second, it makes a contraction of “Bob” with the verb “is.”

The letter S is an accomplice in the confusion. Besides working with apostrophes to form possessives, S has the special job of forming plurals: one cat, two cats.

When the unique properties of S intersect with the confusing role of the apostrophe, look out. For example, you use S to make “cat” plural (cats), but you also use S to make it possessive (cat’s). So it can be a dizzying prospect to make a word plural and also possessive: cats’.

The rule is simple: to make a singular possessive, add an apostrophe plus S. To make a plural possessive, add an apostrophe only after the plural S: cats’.

Of course, some plurals don’t end with S, like children and gentlemen. To make them possessive, use the same formula you use for singular words: add an apostrophe plus S: The children’s books, the gentlemen’s meeting.

Yet another complication: Some singular words end with S: boss, kiss, gas. To make these plural, you usually add not just S but ES: bosses, kisses, gases. But making matters even worse, dictionaries allow both gases and gasses as the plural of gas.

And just when you thought it couldn’t get any more complicated: Style guides disagree on how to make a possessive out of a singular word ending in S. Some say to add the apostrophe alone: the boss’ chair; James’ house. Others say to add another S: the boss’s chair; James’s house. Both are correct.

Amazingly, some of the most common apostrophe errors have nothing to do with this web of complications. More often, people think a word such as luau or Ohio or zebra looks funny with an S at the end. So they toss aside the rule that says don’t use apostrophes to form a plural: “There are several luau’s to choose from.” “It’s like we’re living in two different Ohio’s.” “It was a whole herd of zebra’s.”

None of those should have an apostrophe. Numbers, letters and initialisms don’t need them, either, unless the plural is confusing without them. “We sell DVDs” doesn’t need an apostrophe in the lowercase. But on a storefront written in all caps, an apostrophe can help show which letters are part of the abbreviation: WE SELL DVD’S. That’s acceptable. But only when necessary.

JUNE CASAGRANDE is the author of “The Best Punctuation Book, Period.” She can be reached at JuneTCN@aol.com.