What is the meaning of O.K.?

noun

• An endorsement.
  • usage: "they gave us the O. K. To go ahead"
  • synonyms: OK, okay, okey, okeh

verb

• Give sanction to.
  • usage: "I approve of his educational policies"
  • synonyms: approve, okay, sanction

adjective

• Being satisfactory or in satisfactory condition.
  • usage: "an all-right movie"; "the passengers were shaken up but are all right"; "is everything all right"; "everything's fine"; "things are okay"; "dinner and the movies had been fine"; "another minute I'd have been fine"
  • synonyms: all right, fine, ok, okay, hunky-dory

adverb

• In a satisfactory or adequate manner."she'll do okay on her own"; "held up all right under pressure"; (`alright' is a nonstandard variant of `all right')
  • synonyms: okay, all right, alright