συνεξαμαρτάνειν
From LSJ
Ποιητὴς, ὁπόταν ἐν τῷ τρίποδι τῆς Μούσης καθίζηται, τότε οὐκ ἔμφρων ἐστίν → Whenever a poet is seated on the Muses' tripod, he is not in his senses
Greek > English (Woodhouse Verbs Reversed)
(see also συνεξαμαρτάνω): join in a mistake
