I. ˈhwī, ˈwī adverb
Etymology: Middle English, from Old English hwȳ, instrumental case of hwæt what — more at what
Date: before 12th century
: for what cause, reason, or purpose
why did you do it?
II. conjunction
Date: before 12th century
1. : the cause, reason, or purpose for which
know why you did it
that is why you did it
2. : for which : on account of which
know the reason why you did it
III. noun
( plural whys )
Date: 13th century
1. : reason , cause
wants to know the why s and wherefores
2. : a baffling problem : enigma
IV. interjection
Date: 1519
— used to express mild surprise, hesitation, approval, disapproval, or impatience
why , here's what I was looking for