From Middle English bad, badde (“wicked, evil, depraved”), probably a shortening of Old English bæddel (“hermaphrodite”) (cf. English much, wench, from Old English myċel, wenċel), from bædan (“to defile”), from Proto-Germanic *bad- (cf. Old High German pad (“hermaphrodite”)), from Proto-Indo-European *bʰoidʰ- (cf. Welsh baedd (“wild boar”), Latin foedus (“foul, filthy”), foedō (“to defile, pollute”)).

From Wiktionary

From Middle English bad, from Old English bæd, first and third-person singular indicative past tense of biddan (“to ask”).

From Wiktionary

Middle English badde perhaps from shortening of Old English bæddel hermaphrodite, effeminate or homosexual male

From American Heritage Dictionary of the English Language, 5th Edition

Probably identical to bad, etymology 1, above, especially in the sense "bold, daring".

From Wiktionary

Unknown

From Wiktionary