The most understood word on Earth started as a newspaper joke misspelling

"OK" first appeared in print in a Boston newspaper in 1839 as part of a fad for jokey abbreviations of intentionally misspelled phrases: "oll korrect" for "all correct." The joke should have died out, but the word got a lucky boost from an 1840 political campaign and never stopped spreading; linguist Allan Metcalf argues it's now the most widely recognised word on the planet.

— Allan Metcalf, OK: The Improbable Story of America's Greatest Word — 2010 (etymology traced by Allen Walker Read, 1963-64)
Go deeper: get the book →