πεμπταῖος
From LSJ
λίγεια μινύρεται θαμίζουσα μάλιστ' ἀηδών → the sweet-voiced nightingale mourns constantly, the sweet-voiced nightingale most loves to warble
English (LSJ)
α, ον,
A on the fifth day, mostly agreeing with the Subject, π. ἱκόμεσθα on the fifth day we came, Od.14.257, cf. Hp. Aph.4.36; π.γεγενημένος born five days before, Pi.O.6.53; πεμπταῖα λογίζομαι . . γενέσθαι D.19.59; προκεῖσθαι π. to have been five days laid out as dead, Ar. Av. 474; [νεκροὶ] ἤδη ἦσαν π. X.An.6.4.9; ἔκρινεν [ὁ πυρετὸς] πεμπταίοισι came to a crisis with those who had had it five days, Hp.Epid. 1.20; π. ἀπὸ τῆς νίκης, ἐκ γενετῆς, Plu. Fab.17, Luc. Halc.5. II every fifth day, π. πυρετοί quintan fevers, Hp. Epid.1.24, cf. Alex. Aphr.Pr.2.10; ποτισμοί POxy.729.24 (ii A.D.).