συμμανθάνω
From LSJ
ταῦτα δηλώσω αὐτός τε νοσήσας καὶ αὐτὸς ἰδὼν ἄλλους πάσχοντας → I shall describe those symptoms, since I myself had the disease and witnessed as well what others were suffering
English (LSJ)
A learn along with, share in the knowledge, τινι X.Smp. 2.20; ὁ συμμαθών one that is accustomed to a thing, Id.An.4.5.27; οὐδεὶς ἐπίσταταί με συμμαθεῖν τόπος no place knows that I have shared its secret, S.Aj.869 (lyr., s.v.l.; διδάξαι Sch.).