There are many explanations for the origin of the term OK. Some date the term, which is essentially an agreement or an assent, back to the Native American term “okeh” which means an agreement. Others say the term came from African American slaves. Some connect it to the Greek olla kalla which means “all good.”
Actually, these explanations are specious. We have precise written information regarding the origins of OK. It dates from the 1840 Presidential run of Martin Van Buren, and the OK club, which supported him. OK was an abbreviation of Old Kinderhook. Kinderhook, New York, was where many of the club members were from, thus the word has a double meaning.