νεανικέω
From LSJ
καὶ ὑποθέμενος κατὰ τῆς κεφαλῆς φέρειν τὰς πληγάς, ὡς ἐν ἐκείνῃ τοῦ τε κακοῦ τοῦ πρὸς ἀνθρώπους → and having instructed them to bring their blows against the head, seeing that the harm to humans ... (Josephus, Antiquities of the Jews 1.50)
English (LSJ)
A to be youthful, Eup. 109.
Greek (Liddell-Scott)
νεᾱνῐκέω: εἶμαι νεανικός, Εὔπολις ἐν «Δήμοις» 26.