WHY


Meaning of WHY in English

■ interrogative adverb for what reason or purpose.

■ related adverb (with reference to a reason) on account of which; for which.

↘the reason for which.

■ exclamation

1》 expressing surprise or indignation.

2》 used to add emphasis to a response.

■ noun ( plural ~s ) a reason or explanation.

Origin

OE hwī , hwȳ 'by what cause', instrumental case of hwæt 'what', of Gmc origin.

Concise Oxford English vocab.      Сжатый оксфордский словарь английского языка.