* αὐτοκρατία (autokratía): This is the most straightforward option, as it's a direct borrowing from the English word. While not ancient Greek, it's understood and widely used. It literally translates to "self-rule" or "rule by oneself," capturing the core meaning of autocracy.
* μοναρχία (monarchía): This translates to "monarchy." While not identical to autocracy (a monarchy can be constitutional), it often overlaps significantly, particularly in cases of absolute monarchies which are essentially autocracies.
* Terms emphasizing *sole* rule or *unlimited power* could also be used, depending on context: Words like ἀρχή (archē) (rule, authority), combined with descriptive adjectives like μόνος (monos) (alone) or ἀπεριόριστος (aperioristos) (unlimited) could convey the meaning. For example, μοναρχική ἀρχή (monarchikē archē) – "monarchical rule" – or a phrase like ἀρχὴ μόνου ἀνδρός (archē monou andrós) – "rule of a single man"— could be used.
In short, αὐτοκρατία is the closest and most commonly used modern Greek equivalent, but the best choice depends on the specific context and the aspect of autocracy you wish to highlight.