'arch-scoundrel' is a compound formed from the prefix 'arch-' and the noun 'scoundrel'. 'arch-' originates from Greek 'arkhós' where 'arkhós' meant 'chief' or 'principal'. 'scoundrel' is attested in Middle English as 'scoundrel' (16th century) and denotes a worthless or dishonorable person.

The prefix 'arch-' entered English via Latin/French use in compounds (e.g. 'archbishop') to mean 'principal' or 'chief'. 'Scoundrel' appeared in Early Modern English to label a worthless or villainous person. The compound 'arch-scoundrel' developed later in English by combining the intensifying prefix with 'scoundrel' to denote the 'chief' or 'worst' scoundrel.

Originally the elements separately meant 'chief' (arch-) and 'dishonorable person' (scoundrel); when combined the meaning — 'the principal or extreme scoundrel' — has remained consistent as an intensifying compound.