Merriam-Webster Online Dictionary
why (adverb)for what cause, reason, or purpose - why did you do it?
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
1.
- reason cause wants to know the whys and wherefores
2.
a baffling problem - enigma
- used to express mild surprise, hesitation, approval, disapproval, or impatience why, here's what I was looking for
Merriam-Webster Online Thesaurus
why (noun)1.
something (as a belief) that serves as the basis for another thing
SYNONIMS:
account, authority, grounds, motive, subject, wherefore, whyRELATED WORDS:
antecedent, cause, consideration, impetus, incentive, inspiration, instigation, occasion, stimulus2.
something hard to understand or explain
SYNONIMS:
closed book, conundrum, enigma, head-scratcher, mystification, puzzle, puzzlement, riddle, secretRELATED WORDS:
brainteaser, case, challenge, knot, matter, perplexity, poser, problem, stumper, troublehow surprising, doubtful, or unbelievable
SYNONIMS:
ah, aha, come on, fie, indeed, my word, pshaw, well, what, whyRELATED WORDS:
gee, gee whiz, ha, hello, hey, lo, oh; fiddlesticks, phooey, pooh; there; oops ( whoops woops), ugh; egad, gad, gadzooks [], the deuce, the devil, the dickens, zounds