OK stands for ‘oll korrect’, or ‘ole kurreck’, and comes from an abbreviation trend which was popular in Boston, MA, back in the 1830s. Other popular abbreviations at the time were NG, (‘no go’), GT (‘gone to Texas’) and SP (‘small potatoes’). Many of the abbreviations were deliberately spelt incorrectly for humorous effect; for example, a predecessor of OK was supposedly OW (‘oll wright’). OK gained widespread use when supporters of the American Democratic political party stated that it stood for the nickname of presidential candidate Martin Van Buren, aka Old Kinderhook. ‘Vote for OK’ became a snappy campaign slogan that popularised the use of OK across the USA.
Answered by Rik Sargent.