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.
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.