LSJ
ον, false, vain, Hsch. ; — Lyc. 1420 has ψαίνυνθα θεσπίζειν prophesy falsely (formed like μίνυνθα).
Liddell-Scott-Jones, Greek-English Lexicon (9th ed., 1940)
Pape
ον, = ψαίνυθος, Hesych., der erkl. ψευδές, μάταιον, εὐτελές. Vgl. ψινύθιος.
Pape, Griechisch-deutsches Handwörterbuch (3. Aufl., 1914)