ἀναγκαίη
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)
ἡ, Ep. and Ion, for ἀνάγκη, Il.6.85, Tyrt.6, Sol.36.8, Hdt.1.11, etc.
German (Pape)
[Seite 183] fem. von ἀναγκαῖος, als substant. Homerisch = ἀνάγκη, das adjectiv. statt des subst., wie z. B. παρθενική statt παρθένος u. s. w. Iliad. 4, 300 ἀναγκαίῃ πολεμίζειν; 6, 85 Od. 19, 73 ἀναγκαίη γὰρ ἐπείγει; Her. 1, 74.
Greek (Liddell-Scott)
ἀναγκαίη: ἡ, Ἐπ. καὶ Ἰων. ἀντὶ ἀνάγκη, Ὅμ., Τυρτ., Σόλων, Ἡροδ., κτλ.