ἀΐδηλος
From LSJ
Ἀδώνι' ἄγομεν καὶ τὸν Ἄδωνιν κλᾴομεν → We conduct the rites of Adonis, we weep for Adonis (Pherecrates, fr. 170)
English (LSJ)
[ῐ], Dor. ἀΐδᾱλος, ον, (ἀ- priv., Φιδεῖν)
A making unseen, annihilating, destructive: in Hom., as epith. of Ares and Athena, Il.5.897,880; πῦρ ἀ. 2.455, al., Emp.109; ἠελίοιο ἔργ' ἀΐδηλα Parm.10.3; ἀΐδαλος τύχα Epigr.Gr.240.5 (Smyrna); ἄτη Opp.H.2.487; πότμος ib.1.150. Adv. -λως, = ὀλεθρίως, Il.21.220. II Pass., unseen, unknown, obscure, v.l. in Il.2.318, cf. Hes.Op.756, A.R.1.102, al.; unforeseen, ib.298; formless,4.681; unsubstantial, φρίκη Nic. Th.727; as epith. of Hades, dark, gloomy, S.Aj.608 (lyr.).