From Longman Dictionary of Contemporary Englishno reasonno reasonspokenNONE/NOTHING used when someone asks you why you are doing something and you do not want to tell them‘Why d’you want to go that way?‘ ’Oh, no reason.' →reason
Examples from the Corpus
no reason• I wake up during the night for no reason. 7.• There is no reason to be fatalistic.• There is no reason why a policeman should not be regarded as the victim of this conduct.• ``Why do you want to go that way?'' ``Oh, no reason.''• There's no reason why it shouldn't have worked.• There s no reason whatsoever we shouldn't be thinking in terms of the championship anyway.• I see no reason why they should not be.• But there was no reason why she shouldn't enjoy a bit of company for the rest of the journey.• There was no reason for this other than a certain unwillingness to emerge from our bondtradingshell.