"Okay" (also spelled "OK", "O.K.") is a colloquial English word denoting approval, acceptance, agreement, assent, or acknowledgment. "Okay" has frequently turned up as a loanword in many other languages.
As an adjective, "okay" means "adequate," "acceptable" ("this is okay to send out"), "mediocre" often in contrast to "good" ("the food was okay"); it also functions as an adverb in this sense. As an interjection, it can denote compliance ("Okay, I will do that"), or agreement ("Okay, that's good"). As a verb and noun it means "assent" ("The boss okayed the purchase," and, "The boss gave his okay to the purchase.") A versatile discourse marker (or back-channeling item), it can also be used with appropriate voice tone to show doubt or to seek confirmation ("Okay?" or "Is that okay?").