χαλίνωσις
From LSJ
εἰ ἀποκρυπτόντων τῶν Μήδων τὸν ἥλιον ὑπὸ σκιῇ ἔσοιτο πρὸς αὐτοὺς ἡ μάχη καὶ οὐκ ἐν ἡλίῳ → if the Medes hid the sun, the battle would be to them in the shade and not in the sun
English (LSJ)
εως, ἡ,
A bridling, X.Eq.3.11 (pl.), v.l. in Poll.1.184.
German (Pape)
[Seite 1328] εως, ἡ, das Zäumen od. Aufzäumen, Xen. equ. 3, 11.