ἀρχισύμμαχος
From LSJ
ὁ χρόνος ἐστὶ δάνος, τὸ ζῆν πικρός ἐσθ' ὁ δανίσας → time is a loan, and he who lent you life is a hard creditor | time is on loan and life's lender is a prick
-ου, ὁ encargado de correos, jefe de mensajeros, PKlein Form.314.2 (V/VI d.C.), 271.3, PLaur.93.4 (ambos VI d.C.).