The headword adjective is in the masculine nominative singular; this is presumably generated by the genitive plural in the quotation given.
[1] Likewise (twice over) in ps.-Zonaras.
[2] Theophylact Simocatta, Histories 6.5.5-6; on the citizens of Thracian Drizipera (Drizipara, Drousipara; near the modern-day town of Büyükkarıştıran in European Turkey; Barriongton Atlas map 52 grid B2), under a week-long siege by the Avars in 593; cf. de Boor (228) and Whitby (165). The abridgment by the Suda and ps.-Zonaras is misleading. Whereas the lexicographers here transmit e)cexw/roun tou= a)/steos, Simocatta in fact reads ei)s e)pi/plaston qra/sos e)foi/thsan: "they resorted to a false audacity". The citizens executed a feigned sally from the city gates, and it was the Avars that subsequently withdrew from Drizipera; cf. Whitby (165, notes 27-28). On the Avars see generally alpha 18 note.