What is the meaning of Why?

For what cause, reason, or purpose.

1. Introducing a complete question.

   Introducing a complete question.

   With a negative, used rhetorically to make a suggestion.

   Introducing a verb phrase (bare infinitive clause).

   Introducing a noun or other phrase.

   For which cause, reason, or purpose.

   The cause, reason, or purpose for which.

   Reason.

   An exclamation used to express pleasant or unpleasant mild surprise, indignation, or impatience.

   To ask (someone) the question "why?".

   A young heifer.

   Alternative form of wye; the name of the Latin-script letter Y/y.

   you (formal or plural)

   Source: wiktionary.org