OK's origins1 were long a subject of heated debate, with claims ranging from "only kissing" to "Orrin Kendall" (crackers). After 20 years or so of research, Columbia University professor Allen Walker Read finally traced OK to an 1839 article in the Boston Morning Post. Apparently, it was a cutesy acronym of the tongue-in-cheek or erroneous spelling "oll korrect" for "all correct." The acronym was picked up for Martin Van Buren's 1840 presidential campaign--giving it the additional meaning of "Old Kinderhook." (President Van Buren hailed from Kinderhook, New York.)
OK is considered to be the most widely understood American expression in the
world.1
But is it OK to use OK? (and is it OK, O.K., okay,
or okey?)
It is all right (by the way, many grammarians consider "alright" to be all wrong) to use OK in informal speech or writing. However, the expression is considered casual, or conversational, and (like contractions) it should not be used in formal writing.
OK is recognized and used worldwide in all of its various forms: OK (20,000 Usenet documents in AltaVista--some for Oklahoma), O.K. (5000 ), okay (8000), okey (500), oke (200--some parts of names or products, but some definitely instead of OK), and okeh (97). The third edition of the American Heritage Dictionary of the English Language and Merriam Webster's Collegiate Dictionary--Tenth Edition list the form OK first.
OK is used as
a verb meaning "approve"
Would you OK my vacation request?
an adverb or adjective meaning "all right"
She'll manage OK on her own.
The movie was OK.
a noun meaning "approval" or "agreement"
The reviewers gave their OK to his submission.
and an interjection meaning "all right" or "yes"
OK, where were we?
(often used to introduce a point of contention meaning "I accept what
you've said to a certain extent")
OK, but have you considered . . .
So, go ahead and use OK, but not in your report, presentation, or journal article, okeydokey?
By the way, okeydokey (or okeydoke) is a derivative of OK, as is A-OK, which was often heard before and during early U.S. spaceflights.
1Bryson, B.: Made in America--An Informal History of the English Language in the United States. William Morrow and Company, Inc., New York, 1994, pp. 71-72, 205.