Why

1. n. A young heifer.
2. adv. For what cause, reason, or purpose; on what account; wherefore; — used interrogatively. See the Note under What, pron., 1.
3. adv. For which; on account of which; — used relatively.
4. adv. The reason or cause for which; that on account of which; on what account; as, I know not why he left town so suddenly; — used as a compound relative.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.