'archbuffoon' is a modern English compound formed from the prefix 'arch-' + the noun 'buffoon'. 'arch-' ultimately comes from Greek 'arkhi-' (ἀρχι-) meaning 'chief' or 'principal' via Latin/Old French influence, and 'buffoon' comes from Italian 'buffone' / French 'bouffon' (from late Latin/vernacular roots) meaning 'jester'.

'arch-' entered English as a productive prefix from Greek (via Latin and Old French) used to mean 'chief' or 'extreme' (e.g., 'archbishop'). 'buffone'/'bouffon' entered English as 'buffoon' by way of Italian and French in the 16th century. The compound 'archbuffoon' was formed later in modern English by combining these elements to mean an extreme or chief buffoon.

Initially the elements meant 'chief' (arch-) and 'jester' (buffoon); combined, the term conveyed the idea of a 'chief jester' or an especially notable buffoon. Over time it has been used more broadly and often ironically to label someone as an extreme or consummate fool.