relating to the way that your mind works and the way that this affects your behaviour:
Sleep disorders are a serious psychological problem.
Freud's psychological theories
What was the patient's psychological state?
relating to what is in someone's mind rather than what is real:
Max says he's ill, but I'm sure it's psychological.
behaviour intended to make your opponents lose confidence or feel afraid
4 British English informal
the exact time in a situation when you have the best chance to achieve what you want
psychologically disturbed patients