'archtyrant' originates from Greek elements: the prefix 'arch-' (from Greek 'arkhē' / 'arkhos') where 'arkhē' meant 'rule' or 'chief', and 'tyrant' (from Greek 'tyrannos') where 'tyrannos' meant 'absolute ruler'.

'tyrant' entered English via Old French and Latin (Old French 'tirant', Latin 'tyrannus') and became Middle English 'tirant/tyrant'; the combining prefix 'arch-' (via Latin/Greek compounds and later Middle English usage) has long formed emphatic compounds in English, producing compounds such as 'arch-enemy' and, by analogy, 'archtyrant' in Modern English.

Initially the elements meant 'chief' (arch-) and 'absolute ruler' (tyrant); over time the compound has been used emphatically to mean an especially extreme or predominant tyrant or, figuratively, a person who is overwhelmingly domineering in a given context.