Definitions
1.AdverbFor what cause, reason, or purpose.
Introducing a complete question."Why is the sky blue?; Why did you do that?; I don’t know why he did that; Tell me why the moon changes phase.; Why don't you ask her out for dinner?; Why spend money on something you already get for free?; Why not tell him how you feel?; Why him? Why not someone taller?"
2.AdverbIntroducing a complete question."Why is the sky blue?; Why did you do that?; I don’t know why he did that; Tell me why the moon changes phase.; Why don't you ask her out for dinner?"
3.AdverbWith a negative, used rhetorically to make a suggestion."Why don't you ask her out for dinner?"
4.AdverbIntroducing a verb phrase (bare infinitive clause)."Why spend money on something you already get for free?; Why not tell him how you feel?"
5.AdverbIntroducing a noun or other phrase."Why him? Why not someone taller?"
6.AdverbFor which cause, reason, or purpose."That's the reason why I did that."
7.AdverbThe cause, reason, or purpose for which."That is why the sky is blue.; Why most of us volunteer is that we need some fresh air."
8.NounReason."A good article will cover the who, the what, the when, the where, the why and the how.; I don't want to know the whys or the wherefores of your decision."
9.InterjectionAn exclamation used to express pleasant or unpleasant mild surprise, indignation, or impatience."Why, that’s ridiculous!; Why, how kind of you!; Why yes, that’s true."
10.VerbTo ask (someone) the question "why?".
11.NounA young heifer.
12.NounAlternative form of wye; the name of the Latin script letter Y/y.