OK is a word of indigenous origin (Choctaw)

The term OK has been internationalized and is used throughout the world and in different languages. The origin of the word has been attributed to a rather unusual ironic expression "oll korrect" or a military expression O killed. Much more likely is the hypothesis that establishes its origin in the language of the choctaw nation that was the language of relationship (lingua franca) between the Indians and colonists of central and southern North America in the colonial period. In Choctaw Oke means "deal done", "like that". As usual, the descendants of the invaders consciously or unconsciously reject the indigenous roots of their customs and idiomatic expressions. In other words the word OK is of Native American origin. It is worthwhile to know to run the curtains of concealment and cultural genocide of this continent. We include it as one more piece of information in our book "Amerrique, Orphans of Paradise". 

Next a transcription of a site that raises the etymology of OK.

"The" Choctaw Language Dictionary "published in 1915 gives the first evidence of that.As a Christian missionary working with the Choctaw of Mississippi, the author Cyrus Byington cataloged the people's language widely.According to him and even published dictionaries more Later, "Okeh" meant "it is like that and not otherwise." So the origin of the word is reduced to a Native American etymology. "

http://www.swagger.mx/radar/cual-es-el-origen-de-la-palabra-ok