Whether to use a hyphen in "coworker" (or "co-worker") is a matter of style. The Chicago Manual of Style does not use a hyphen, but some other style guides do.
The rules about hyphens are often more like guidelines. You may need both a style guide and a good dictionary to get answers about hyphens. If you find yourself repeatedly looking up words, it helps to keep your own list of how to write potentially hyphenated words.
The word that describes someone you work with is one of the words that can go either way. Associated Press writers, New York Times writers, and New Yorker writers go out to lunch with their co-workers (hyphenated), but Chicago Manual of Style editors go to the co-op with their coworkers (unhyphenated, but they do hyphenate “co-op” because of the double O). I prefer the hyphen with “co-worker” because without it, I always initially think the word is “cow-workers.”
The AP tends to defer to how words are used within their own industries though, and even though they hyphenate “co-worker,” they don’t hyphenate “coworking” because nobody in the coworking industry hyphenates it.
An interesting way to think about hyphens is that they can both join words or word parts, like they do with co-worker, and separate words, like they do when a long word falls at the end of the line and you use a hyphen to break it apart.
Garners’s Modern English Usage says that British English is more accepting of hyphens than American English, but the general trend is away from using hyphens, which you’ll quickly notice if you read old books. For example, “percent,” “fingernail,” and “windowpane” used to be written with hyphens, and now they’re not.
There was a bit of hyphen news at the American Copy Editors Society meeting last week too. The AP Stylebook editors announced they are dropped the hyphen from “3D” and “Walmart,” and Merriam-Webster lexicographer Peter Sokolowski announced the dictionary is dropping the hyphen from the words “copyediting” and “goodbye.” They even had pins that said “Goodbye hyphen” (with “goodbye” spelled without the hyphen.)
That’s your Quick and Dirty Tip: Although in general, fewer and fewer English words are hyphenated with each style guide and dictionary update, most style guides still recommend hyphenating “co-worker,” except The Chicago Manual of Style, which writes it as one closed up word: “coworker.”
Mignon Fogarty is Grammar Girl and the founder of Quick and Dirty Tips. Check out her New York Times best-seller, “Grammar Girl’s Quick and Dirty Tips for Better Writing.”
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