'O.K.' definitions:

Definition of 'O.K.'

(from WordNet)
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') [syn: okay, O.K., all right, alright]
adjective
Being satisfactory or in satisfactory condition; "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" [syn: all right, fine, o.k., ok, okay, hunky-dory]
noun
An endorsement; "they gave us the O.K. to go ahead" [syn: O.K., OK, okay, okey, okeh]
verb
Give sanction to; "I approve of his educational policies" [syn: approve, O.K., okay, sanction] [ant: disapprove, reject]