πενθήμερος
From LSJ
Έγ', ὦ ταλαίπωρ', αὐτὸς ὧν χρείᾳ πάρει. Τὰ πολλὰ γάρ τοι ῥήματ' ἢ τέρψαντά τι, ἢ δυσχεράναντ', ἢ κατοικτίσαντά πως, παρέσχε φωνὴν τοῖς ἀφωνήτοις τινά –> Wretched brother, tell him what you need. A multitude of words can be pleasurable, burdensome, or they can arouse pity somehow — they give a kind of voice to the voiceless.
English (LSJ)
ον,
A of five days, ἀγών Sch. Pi.O.5.13 ; κατὰ πενθήμερον for alternate periods of five days, X.HG 7.1.14 ; once in every five days, Arist.Ath.30.4 ; also καθ' ἑκάστην πενθήμερον SIG364.9 (Ephesus, iii B. C.).
German (Pape)
[Seite 555] fünftägig, κατὰ πενθήμερον ἑκατέρους ἡγεῖσθαι, Xen. Hell. 7, 1, 14, abwechselnd