"OK" is one of the most common words in the English language, but linguistically it's a relative newbie. It's just 150 years old, and traces its roots back to 19th century Boston. Rather than anyone purposefully inventing "OK," it's actually editorial joke that inadvertently went viral.
It all began in the office of Charles Gordon Greene at the Boston Morning Post, Good Magazine writes. The year was 1839, and among writerly folk, abbreviations were all the rage (think LOLZ, OMG or NBD today). "This trend," Good continues, "produced many unsuccessful terms such as OW—an OK-like term for “oll wright” (all right) that flopped."
OK first appeared as an abbreviation for “Oll Korrect,” printed in a satirical article about grammar, the Economist continues. The word's origins were only revealed in the 1960s, however, when etymologist Allen Read did some digging—through suggestions that the word might come from Europe, a Civil War nickname for biscuits, or an abbreviation for the telegraph term Open Key. Still others falsely thought that president Martin Van Buren had invented the term in his presidential campaign, which used the slogan "Vote for OK" in reference to both his hometown and his nickname, Old Kinderhook, the Economist writes. But Van Buren only popularized the term, Read found, not invented it.
Although Read showed "how, stage by stage, OK was spread throughout North America and the world to the moon, and then took on its new form AOK, first used by space people and frowned on by purists," the Economists writes, some doubters continue to insist that the word in fact has a much earlier origin. We'll just have to be OK with never knowing for absolute sure.