You Could Look It Up

A. If you’re an American traveler who’s traveling in the United States, use one l; if you’re a British traveller travelling in the UK, use two. But if you plan on excelling in either region, you’ll want to use two l’s for that word.

That’s because of two competing conventions: (1) When -ing or -ed (or -er) is added to a word of two or more syllables that ends in a consonant preceded by a single vowel (like travel and excel), the consonant is usually doubled if the stress falls on the final syllable. Accordingly, you’d write traveling and traveled (because the stress in travel is on the first syllable) but excelling and excelled (the stress in excel is on the second). But (2) travelling and travelled (and traveller) are exceptions to the rule in British but not American usage.

We don’t know the reason for that exception, but we can offer as evidence this footnote from page 16 of the eighteenth edition of Horace Hart’s Rules for Compositors and Readers at the University Press, Oxford (published in 1904, the first year Hart’s guide was offered to the public):

We must, however, still except the words ending in -el, as levelled, -er, -ing; travelled, -er, -ing; and also worshipped, -er, -ing.—J. A. H. M.

That footnoted exception applies to the rule about not doubling consonants when the last syllable isn’t stressed. “J. A. H. M.” is James Murray, the main editor of the original Oxford English Dictionary, who is also credited on the title page of that edition (and others) of Hart’s Rules as one of two people responsible for revising its “English spellings.”

The three exceptions noted in the footnote above are still followed in British English. In American English, by contrast, level and (as we have seen) travel do not double the l, but worship usually doubles the p (as in British English).

CMOS used to include a list of preferred spellings—as on pages 37 and 38 of the first edition (published 1906), which showed traveler with one l and (in a decision backed by logic that nonetheless didn’t stick) worshiper with one p. CMOS now defers to Merriam-Webster for such decisions.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. The most common plural form of the noun hoof in American English is hooves. In British English, it’s hoofs. You can glean this information from the entries for hoof at Merriam-Webster.com (which records common American usage) and in the OED (which reflects British usage).

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. For anyone or anything that flies, use flier. For the advertising circular, which isn’t usually circular (the name is related to circulation), use flyer.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. Merriam-Webster includes an entry for “Gen Z” as a noun. Under “Other Words from Gen Z,” the entry lists “Gen Zer or Gen-Zer” and “Gen Zers or Gen-Zers” (“or” means the hyphenated variants are equally common, but in such cases Chicago normally advises choosing the first-listed form). You won’t, however, find “Gen Zs”—which you can therefore assume occurs only as the plural form of “Gen Z,” as in more than one Generation Z (see CMOS 7.15 for styling the plurals of letters). For members of Generation Z, then, write “Gen Zers.” Ditto for their predecessors: “Gen Yers” and “Gen Xers.”

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. “OK” and “okay” are informal, so even though we might normally choose the first-listed “OK” in Merriam-Webster (rather than its equal variant “okay”), it doesn’t really matter which form of this handy nineteenth-century abbreviation you prefer. Both appear in CMOS 17, all but once as “OK” in examples that feature informal prose (and not counting its appearance as an abbreviation for Oklahoma). The one time the term appears in our own explanatory text, we chose “okay,” which looks more like a real word (see CMOS 14.5, first bullet point). In texts or email, you’ll face a different set of choices that are beyond the scope of CMOS. But if you can somehow manage to strike a balance between personal preference, on the one hand, and considerations related to context, desired tone, audience, and the changing fashions of internet language, on the other, you should be just fine (as in A-OK). Okeydoke?

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. All of the above. According to Merriam-Webster, the expression is spelled out “twenty-four seven” and can be abbreviated either “24-7” or “24/7” (the latter two are equal variants, which M-W separates by “or”). The entries for the spelled-out and abbreviated forms are separate in M-W, so you’ll have to make a choice. If you are spelling out numbers zero through one hundred (per CMOS 9.2), opt for “twenty-four seven”; if you’re spelling out only single-digit numbers (per CMOS 9.3), choose the first-listed abbreviation in M-W and go with that. There’s no harm, of course, in opting for the second-listed equal variant if that’s what you prefer, but whatever you do, be consistent—twenty-four hours a day, seven days a week.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. Probably only in a hashtag—#StyleGuide or #styleguide (hashtags aren’t case sensitive, and Chicago style allows for either). Guide, unlike book, doesn’t tend to form one word unless it’s at the beginning. So style guide but stylebook and guidebook. For answers to questions like this one, Merriam-Webster is our go-to guide.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. Yes, it is. Please see CMOS 5.216 (“Exclamations”). (Tip: You can find a word in CMOS by typing it into the search box.)

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. Yes. But so far, there has never been a dictionary that listed all the words. There are too many words! One of the standards that lexicographers use when deciding which words to delete to make way for new ones is whether a word is actually used very often in a meaningful way. At least one online dictionary, Wordnik, has a goal of listing all the words available. Qobar isn’t listed there yet—maybe you should send it!

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. It’s true—the lexicographers at M-W can’t be everywhere at once, which leaves discrepancies between their various versions. But the kinds of changes you’re talking about are minor. It’s not as though life span is now so grossly incorrect that using it would invite viral shaming on Twitter. We hyphenate a compound to make it easier to read or to prevent misreading. If you use common sense and keep a style sheet, you needn’t worry about whether you’re up to the minute with M-W.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]