From Longman Dictionary of Contemporary Englishdefeat the purposedefeat the purposeto fail to achieve the result you want Anxiety will cause tension, which defeats the purpose of the exercise (=the activity or plan). → purpose
Examples from the Corpus
defeat the purpose• They are defeating the purpose of the Peace Corps and they are unhappy.• This, of course, defeats the purpose for which the medication is being given.• Never remove them and forget to put them back, it defeats the purpose.• This obviously defeated the purpose of bail, which is to assure that the defendant will appear in court.• If they become a chore, they defeat the purpose of helping the child to want to interact with you.• Doesn't this defeat the purpose of producing fruit in the first place?• This anxiety will cause tension which defeats the purpose of the exercise.• This also eliminates the need to scroll to find data, which would defeat the purpose of having a command centre. 