Q. I am copyediting an article about a brand of software. The article repeatedly uses the term dialog, but Merriam-Webster’s 11th Collegiate Dictionary prefers the spelling dialogue. However, the software uses dialog in all its documentation. Which spelling does CMOS prefer in this case? Thank you.
A. M-W shows dialog as a “secondary variant,” which means that it is standard English and may be used according to preference. Typing dialogue into the CMOS Search box, I see that CMOS happens to use that form. If a writer prefers dialog for a good reason, however (such as that it’s standard parlance in techspeak), an editor who changes it should have an even better reason, since it is not incorrect.