Language always is in a slow transition where spelling, pronunciation, definitions, and – more glacially –the grammar itself, is concerned. The competing spellings of co-worker and coworker is among those words in our language now undergoing just such a change.
Traditionally, co-worker is considered correct. As the Associated Press Stylebook still notes, typically words that denote position or occupation require a hyphen. Such words include co-author, co-owner and co-star.
The Chicago Manual of Styles 16th edition, however, lists coworker as not requiring a hyphen, a change from its 15th edition which allowed for either spelling. From personal experience as an editor, I’ve increasingly noticed writers using coworker without a hyphen, suggesting the 16th edition’s influence on writing and publishing.
Bottom Line: Use the style that your publisher prefers – if writing a magazine or newspaper article, that likely means AP style; if writing a book, that likely means Chicago Manual – and be internally consistent by always using the same style throughout your manuscript.
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My name is Rob Bignell. I’m an affordable, professional editor who runs Inventing Reality Editing Service, which meets the manuscript needs of writers both new and published. I also offer a variety of self-publishing services. During the past decade, I’ve helped more than 300 novelists and nonfiction authors obtain their publishing dreams at reasonable prices. I’m also the author of the 7 Minutes a Day… writing guidebooks, four nonfiction hiking guidebook series, and the literary novel Windmill. Several of my short stories in the literary and science fiction genres also have been published.