Definition of why

• adv. - For what cause, reason, or purpose; on what account; wherefore; -- used interrogatively. See the Note under What, pron., 1.
• adv. - For which; on account of which; -- used relatively.
• 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.
• n. - A young heifer.