the word 'wackiness' is a modern english formation built upon the colloquial adjective 'wacky', which emerged in american slang during the 1930s. 'wacky' itself is believed to be a variant of 'whacky', potentially derived from the verb 'whack' meaning to strike, suggesting the notion of being 'whacked out' or mentally unsettled. the suffix '-ness', of germanic origin and one of the most productive in english for forming abstract nouns, was appended to create a term for the abstract quality of eccentricity. thus, the literal construction 'the state of being wacky' cleanly evolved into the modern meaning denoting silly or irrational behaviour.

Structure: wack (silly, crazy) + i (connective) + ness (state or quality) - wack: (origin: mid-20th century american english, likely a shortening and alteration of 'whacky' or 'wacko') the core root conveying the sense of being irrational or eccentric. - i: (origin: english) a connective vowel used for euphony when adding suffixes. - ness: (origin: old english '-nes', '-ness') a noun-forming suffix indicating a state, quality, or condition.