ναύαρχος – nauarchos

The commander of the Greek city-states’ navies, roughly equivalent to “admiral,” or frequently rendered in English as “nauarch.”

In Hellenica, III.iv.27:
καὶ καταστήσασθαι ναύαρχον ὅντινα αὐτὸς βούλοιτο.
and to appoint nauarch whoever he might wish.

In Hellenica, III.iv.29:
Πείσανδρον δὲ τὸν τῆς γυναικὸς ἀδελφὸν ναύαρχον κατέστησε,
And he appointed Peisandros, the brother of his wife, nauarch,

Greek used the -arch suffix a lot, for ‘commander.’ So there is phyl-arch (commander of a phyle, or tribe), and hipp-arch, for ‘cavalry commander,’ etc. So, some translators simply Anglicize the Greek word, rather than struggle with an English equivalent. It’s a choice that comes up with weights and measures. When the Greek says “four stadia,” one can render that as “four stadia” (maybe with a footnote), or say “four hundred feet” which would be the equivalent. When one’s goal is just to make sure that you, yourself, the translator knows what’s going on, it’s easier to use ‘nauarch, stadia,’ etc. rather than an approximate translation.