Why we say OK — a Vox Explainer article about how a shorthand expression that came about during the late 1830s became one of the most common expressions. Via the Nerdist:
In the list of the most commonly used words in the English language, there are plenty that are obvious inclusions. “The,” “a,” “it,” and other words that we use every day are on it, including “OK.” Of them all, though, “OK” is perhaps the strangest. What does the two-letter word actually mean? Where did it come from? It’s a word with an interesting history, a history that’s broken down and evaluated in a new video from Vox.
It turns out that the word emerged about 200 years ago: In the 1830’s, folks had a thing for intentionally misspelling abbreviations because they thought it was pretty darn funny. One of those abbreviations stuck: “OK,” which was short for “oll korrect,” or “all correct.” “OK” hit the big time when it was used in an issue of the Boston Morning Post in 1839. Other newspapers took note and spread the word around the country. From there, it was further popularized by President Martin Van Buren, and then the rise of the telegraph, since the word was easy to tap out and it sounded distinct from other words. The video goes on to explain other fascinating factors related to the rise of “OK,” such as the use of the letter K in branding and marketing, that led to it being the ultimate “neutral affirmative” word of today.