ψό
From LSJ
Δύο γὰρ, ἐπιστήμη τε καὶ δόξα, ὧν τὸ μὲν ἐπίστασθαι ποιέει, τὸ δὲ ἀγνοεῖν → Two different things are science and belief: the one brings knowledge, the other ignorance (Hippocrates)
English (LSJ)
a shepherd's call, S.Fr.521, cf. Ael.Dion.Fr.337. II an exclamation of disgust or contempt, pshaw! Phot.; dub. in A.Fr.82, Ar.Fr.892/3.
German (Pape)
[Seite 1401] ein Ausruf des Ekels, Widerwillens, Abscheues, pfui; Phot.; Soph. frg. 461 im E. M.; Hdn. περὶ μον. λ. p. 46.