κιθαριστέον
From LSJ
ἢ λέγε τι σιγῆς κρεῖττον ἢ σιγὴν ἔχε → either say something better than silence or keep silence (Menander)
English (LSJ)
one must play the cithara, Pl.Sis. 389c.
Greek (Liddell-Scott)
κῐθᾰριστέον: ῥημ. ἐπίθετ., δεῖ καθαρίζειν, Πλάτ. Σίσυφ. 389C.
Dutch (Woordenboekgrieks.nl)
κιθαριστέον, adj. verb. van κιθαρίζω, er moet op de citer worden gespeeld.