'archpatron' is formed from the prefix 'arch-' (from Greek 'arkhós') meaning 'chief' or 'principal', combined with 'patron' (from Latin 'patronus') meaning 'protector' or 'supporter'.

'patron' comes from Latin 'patronus' > Old French 'patron' > Middle English 'patron'. The prefix 'arch-' derives from Greek 'arkh-' via Latin/Old French use as a formative element; the compound 'archpatron' has been created in modern English by combining these elements to denote a 'chief patron'.

Initially the elements meant 'chief' + 'protector'; over time the compound has been used to mean 'principal supporter' or 'foremost benefactor' in modern usage.