OK began as a joke about deliberately bad spelling

Everything below about the origin of the word OK comes from what actually happens rather than from what is supposed to.

A fad for silly abbreviations

Newspapers in the north-eastern United States in the 1830s ran a craze for humorous abbreviations of deliberately misspelled phrases. Writers produced initials for phrases like no go rendered as know go, and the joke lay in the double layer of error. The fad was short-lived and produced dozens of such forms, almost all of which vanished within a few years.

One of them abbreviated a comic misspelling of all correct, and it appeared in print in a Boston newspaper in 1839. The documentation for this was assembled by a linguist who worked through the newspaper record in detail.

The campaign that saved it

The following year, supporters of a presidential candidate formed clubs using his nickname, which derived from his home town. That nickname abbreviated to the same two letters, and the coincidence gave the abbreviation an enormous boost. Political slogans reach far more people than newspaper in-jokes, and the campaign carried it across the country.

Opponents also used it in attacks, which spread it further, as hostile repetition generally does. By the time the election was over, the two letters had escaped both the joke and the campaign.

Why it survived when the others did not

It is short, easy to say in almost any language, and made from two very distinct sounds that resist being misheard. It also fills a genuine gap, expressing acceptance without enthusiasm, which few other words in English do concisely. Telegraph operators adopted it because brevity mattered and it was unambiguous, which reinforced its spread.

The primary source says otherwise: it has since been borrowed into a very large number of languages, often with the same spelling and roughly the same meaning. Few English words have travelled so widely, and none with such a trivial origin.

The competing explanations

Alternative origins have been proposed involving West African languages, Choctaw, Scottish dialect, Greek and several military abbreviations. Some of these are more plausible than others, and the question of whether an existing similar word helped it catch on is genuinely open. What the newspaper record establishes is the documented first appearance and the mechanism of its spread.

Checked against the record, that does not rule out reinforcement from other directions, which is often how a word becomes established.

The confident single-origin story and the confident dismissal of all alternatives are both slightly stronger than the evidence.

The form it takes now

It functions as an adjective, an adverb, a noun, a verb and a discourse marker, which is unusual flexibility for two letters. The longer spelling emerged later and is now used more or less interchangeably, with the shorter form dominating in writing. It has produced derivatives including a doubled emphatic form and various regional variants.

Its meaning has softened over time, and in some contexts it now signals reservation rather than approval. That drift towards lukewarmness is a normal fate for words of general approval, which wear out with use.

Printing a correction has a poor record of taking a myth out of circulation.

Why the origin surprises people

Words this common feel ancient, and it is difficult to accept that one of them can be dated to a specific newspaper column. The triviality of the origin also clashes with the word's importance, which produces a search for something grander.

Somewhere in the retelling, that search is where most of the alternative explanations come from, and several were proposed by serious people. The mundane answer, properly documented, is more interesting than any of them. It is one of the very few words in English whose birth can be pinned to a year and a page.

The takeaway

Two letters from a short-lived newspaper joke are now understood in more languages than any word English has produced since.

Believing it was ordinary. Continuing to is the avoidable part.