ἐρήμωσις
From LSJ
τὸ πλῆθος οὐκ εὐαρίθμητον ἦν → the crowd wasn't easy to count, the crowd was not small, it was not a small crowd
English (LSJ)
εως, ἡ,
A making desolate, LXXLe.26.34, al., Heph.Astr.1.21 ; χωρίου Arr.An.1.9.7 ; βδέλυγμα τῶν ἐ. LXXDa.9.27, cf. Ev.Matt.24.15.
German (Pape)
[Seite 1027] ἡ, die Verwüstung, Arr. An. 1, 9, 13 u. a. Sp.