WACKY Meaning of WACKY in English adj. & n. (also whacky) sl. --adj. (-ier, -iest) crazy. --n. (pl. -ies) a crazy person. Derivatives: wackily adv. wackiness n. Etymology: orig. dial., left-handed, f. WHACK Oxford English vocab. Оксфордский английский словарь. 2012