εὐθύγραμμον

From LSJ

ὕπνος δεινὸν ἀνθρώποις κακόνsleep is a terrible evil for humans (Menander, Sententiae monostichoi 1.523)

Source

Russian (Dvoretsky)

εὐθύγραμμον: τό (sc. σχῆμα) прямолинейная фигура Arst., Plut.