Longman Dictionary of Contemporary English - okay

interjection 1 used when you start talking about something else, or when you pause before continuing  (OK, let's go on to item B. | OK, any questions so far?) 2 used to express agreement or give permission  ("Can I take the car today?" "Okay.") 3 used to stop people arguing with you  (OK, OK, so I made a mistake, I've told you I'm sorry.) 4 used when you think people are being unreasonable  (Look, I'm doing my best, OK?) ~3 v okayed, okaying informal to say officially that you will agree to something or allow it to happen  (Has the bank okayed your request for a loan?) ~4 n informal give (sb) the okay/get the okay to give or get permission to do something  (I got the OK to leave early today.)