why

Universal Words adverb, exclamation, noun adverb 1 used in questions to ask the reason for or purpose of sth: Why were you late? * Tell me why you did it. * 'I would like you to go.' 'Why me?' * (spoken) Why oh why do people keep leaving the door open? 2 used in questions to suggest that it is not necessary to do sth: Why get upset just because you got one bad grade? * Why bother to write? We'll see him tomorrow. 3 used to give or talk about a reason: That's why I left so early. * I know you did it-I just want to know why. * The reason why the injection needs repeating every year is that the virus changes. IDIOMS why ever used in questions to mean 'why', expressing surprise: Why ever didn't you tell us before? why not? used to make or agree to a suggestion: Why not write to her? * 'Let's eat out.' 'Why not?' * Why don't we go together? exclamation (old-fashioned or AmE) used to express surprise, lack of patience, etc: Why Jane, it's you! * Why, it's easy-a child could do it! noun IDIOMS the whys and (the) wherefores the reasons for sth: I had no intention of going into the whys and the wherefores of the situation.