wackyEnglishOxford New American Dictionarywacky /ˈwakē, ˈwæki / (also whacky) ▸ adjective (wackier, wackiest) informal funny or amusing in a slightly odd or peculiar way: a wacky chase movie. – DERIVATIVES wackily /ˈwakəlē, ˈwækəli / (also whackily) adverb,wackiness /ˈwakēnəs, ˈwækinəs / (also whackiness) noun– ORIGIN mid 19th century (originally dialect): from the noun whack + -y1.