Толковый словарь английского языка - why

I. adverb see: what Date: before 12th century for what cause, reason, or purpose , II. conjunction Date: before 12th century the cause, reason, or purpose for which , for which ; on account of which , III. noun (plural ~s) Date: 13th century reason, cause , a baffling problem ; enigma, IV. interjection Date: 1519 — used to express mild surprise, hesitation, approval, disapproval, or impatience <~, here's what I was looking for>