Okay?
This may be a long and difficult post, at least for the poster.
Here’s the entry for OK from etymonline:
1839, only survivor of a slang fad in Boston and New York c.1838-9 for abbreviations of common phrases with deliberate, jocular misspellings (cf. K.G. for “no go,” as if spelled “know go”); in this case, “oll korrect.” Further popularized by use as an election slogan by the O.K. Club, New York boosters of Democratic president Martin Van Buren’s 1840 re-election bid, in allusion to his nickname Old Kinderhook, from his birth in the N.Y. village of Kinderhook. Van Buren lost, the word stuck, in part because it filled a need for a quick way to write an approval on a document, bill, etc. The noun is first attested 1841; the verb 1888. Spelled out as okeh, 1919, by Woodrow Wilson, on assumption that it represented Choctaw okeh “it is so” (a theory which lacks historical documentation); this was ousted quickly by okay after the appearance of that form in 1929. Okey-doke is student slang first attested 1932. Greek immigrants to America who returned home early 20c. having picked up U.S. speech mannerisms were known in Greece as okay-boys, among other things.
From Wikipedia about Occitan languages:
http://en.wikipedia.org/wiki/Occitan_language
The word òc came from Vulgar Latin hoc (“this”), while oïl originated from Latin hoc illud (“this [is] it”). Old Catalan and nowadays the Catalan of Northern Catalonia (France, Catalunya Nord) also have hoc (òc). Other Romance languages derive their word for yes from the Latin sic, “thus [it is], [it was done], etc.”, such as Spanish sí, Eastern Lombard sé, Italian sì, or Portuguese sim. In Modern Catalan, as in modern Spanish, sí is usually used as a response, although the language retains the word oi, akin to òc, which is sometimes used at the end of Yes-no questions and in higher register also as a positive response.[15]