(1):
(adv.) For what cause, reason, or purpose; on what account; wherefore; - used interrogatively. See the Note under What, pron., 1.
(2):
(adv.) For which; on account of which; - used relatively.
(3):
(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.
(4):
(n.) A young heifer.