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- Difference between “OK” and “okay” 10 answers
Whenever I write ok the spell checkers underline it with a red line and suggest that I should OK. Not even Ok works. Why is this so?
OK is Ok, and Ok is OK.
Oh, also Oklahoma is OK. That's its USA postal code, so it's possible that your spell-checker is agnostic on the subject, and just thinks you are trying to use the state of Oklahoma in an address.
I upvoted @camelbrush's answer because it provides a good explanation of the logic behind why some folks prefer to capitalize both letters. However, nobody is really sure where this word came from. Wikipedia has a table of around 30 of the more popular theories (from 13 different languages).
Realistically one just has to accept that both are in common use, and neither is provably "wrong". If the uncertainty really bugs you, just use the word "Okay" instead.
OK is an abbreviation. This is what Oxford online dict says about its origin:
Now, let us look at this style guide about capitalization (Guardian Style Guide):
Here is another style guide that suggests:
But then, different office suites (MS Office, Libre Office, Lotus, etc) imply these rules differently. MS Office accepts both Ok and OK.
The word is usually written OK or okay as it is a verbalization of the letters O and K, and that is simply the accepted spelling.
If I were to read ok or Ok somewhere, I would think it a misspelling of auk.