How should I write abbreviation for "okay"? The options are: ok, Ok, OK.

I've never took any notice of it, but recently someone (that he's not a native English speaker) told me that I should write OK. Is that true?

  • 1
    I would capitalise "OK" except in informal chats, but I note that Merriam-Webster accepts "ok" as a variant. "OK" isn't an abbreviation of "okay". "OK" is the older spelling (though it was originally written with full stops: "O.K."). (There was also at least one very early instance of "o.k.", though "O.K." predominated.)
    – rjpond
    Commented Dec 20, 2017 at 18:48
  • When in doubt, spell it out: okay. (Just pointing out that, in many cases, this may be the best option.)
    – J.R.
    Commented Dec 20, 2017 at 21:22

1 Answer 1


"Ok" is certainly not correct (unless it's starting a sentence), but outside of hyper-standardised contexts you're not going to see anyone differentiating between "ok" or "OK".

Many theories for the etymology centre around it being an initialism of two other words which mean that in theory it should be written as "OK", but it's not uncommon for initialisms to become genericised to the point that they are no longer written as such (see: scuba, radar, laser), and okay is certainly genericised to the point that rules mostly go out the window and the "correct" usage is just what everyone else is already using.

Most publications still stick with "OK" over "ok". Oxford Dictionary uses "OK", as does every single news publication I found when searching Google News for the word. In addition, nearly all of Wikipedia's sources use that capitalisation too, and while that could just be cherry picking from an editor with an absurdly specific bone to pick, it does match up with everything else.

That said, it's certainly not completely consistent. Oxford uses "ok" in lowercase as in "the committee ok'd the construction", and many publications avoid the question entirely by just writing "okay" - it is after all only two letters longer. It's also not unheard of to see "O.K.", although that usage peaked in the 1940s.

In summary, "OK" is the most correct usage (so far as "most correct" can be a thing), but outside of the most hyper-formal context no-one is going to bat an eye at you using "ok".

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