ἄτρεστα

From LSJ

λίγεια μινύρεται θαμίζουσα μάλιστ' ἀηδών → the sweet-voiced nightingale mourns constantly, the sweet-voiced nightingale most loves to warble

Source

Russian (Dvoretsky)

ἄτρεστα: adv. без страха, спокойно (ἐν δόμοις ναίειν Eur.).