The word 'whack' is an onomatopoeic formation from the late 17th century, imitating the sound of a resounding blow. Its use evolved to figuratively mean 'to strike forcefully' and later 'to defeat or overcome'. The participial adjective 'whacked' emerged in 20th-century informal English, drawing on this figurative sense. The primary modern meaning of 'extremely tired' logically extends from the idea of being physically beaten or overcome by exertion, while the sense of being intoxicated derives from the concept of being mentally 'struck' or affected by substances.

Structure: whack (hit) + ed (adjective suffix) 'whack' is an imitative word of English origin, likely from the sound of a sharp blow. The suffix '-ed' is from Old English '-ed', '-od', '-ad', used to form adjectives from nouns or verbs, indicating a state or condition.