'archeunuch' originates from Greek, specifically from the elements 'archē' and 'eunouchos,' where 'archē' meant 'chief' or 'principal' and 'eunouchos' meant 'eunuch' (literally a bed-keeper).

'archeunuch' entered English via Medieval/Latin formations (compare Latin 'archi-eunuchus' or similar compounds) and through usage in historical and scholarly texts it came to appear in Modern English as 'archeunuch.'

Initially it designated the actual office or person who was the chief of the eunuchs; over time it has remained a specialist or historical term and is now chiefly used in historical description or scholarship rather than in contemporary administration.