Full Form of OK is Oll Korrect.
OK is. abbreviation of “All Correct” of standard english, the correct/old pronunciation is something I am not able to recollect as of now
One also suggests that OK is a short form of OKAY.
A lot of researchers have tried to find the origin of “OK”, it is claimed that written records of the term OK is found as back as early 1800’s.
Another interesting school of though claims that it originated during a war when the soldiers from the war front called for back from the reserve, the medium used was telegraph. they would just send a message 4.K. meaning 4 soldiers were killed and 0.K. meaning no-one was killed that day.