If you are chastened by something, it makes you regret that you have behaved badly or stupidly. He has clearly not been chastened by his thirteen days in detention A chastened Agassi flew home for a period of deep contemplation. + chastened chas·tened The President now seems a more chastened and less confident politician than when he set out a week ago. to make someone realize that their behaviour was wrong or mistaken (chaste (12-17 centuries), from chastier, from castigare; CASTIGATE)