Abbreviated from Harpocration s.v., an entry generated by (and quoting more fully than here) Demosthenes 15.9.
Also in Photius.
[1] i.e. the Persian king (Artaxerxes II in the present instance).
[2] hyparchos, 'subordinate governor' or 'deputy ruler', sometimes applied to Persian satraps or their deputies. (The upsilon 160 entry is generic.)
[3] The date is around 370 BC (Shipley, History of Samos 136-7).