Greek Language. . "O.K." is the abbreviation (spelled correctly) of the Greek expression,Ola Kala (Ολα Καλά, ΟΚ) It is a standard expression in Greece that simply means: "Everything's fine". Some teachers still use it to mark good school papers with.. . The abbreviation "OK" was informally used to communicate the "All's well!" (with light or other means) with shore or other ships . Also, for the Captain of a ship, hearing the Ola Kala was a quick way to take stock of a situation. OK did not however signify acquiescence to a command, as in: -“Do this! -“OK!” The expression En Taxe, meaning “in order” would have been used in that case.. . OK was also marked on shipping crates after inspection to signify that everything in them was all right. It is possible that port communities worldwide came in contact with "O.K." thus. Throughout history, the Greek presence on the seas has been disproportionately large compared to the size of the country. The current (2006) Greek merchant fleet, for example, is larger than both US and Japanese fleets combined.