Subscribe to The Chicago Manual of Style Online
You Could Look It Up
Q. According to CMOS, which is the correct use . . . “OK” or “okay”? I’m having difficulty finding the answer to what I hope is an easy question. Thank you!
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?