for what purpose or reason? :
What is this tool for?
What did you do that for (= why did you do that) ?
'I need to see a doctor.' 'What for?'
for what purpose or reason? :
What is this tool for?
What did you do that for (= why did you do that) ?
'I need to see a doctor.' 'What for?'
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005