ἄληπτος · alēptos — LSJ
not to be laid hold of, hard to catch, Plu. Sert. 16, Poll. 5.169, etc.; ἄ. τοῖς ἐχθροῖς J. AJ 5.8.11: in Comp. ἀληπτότερος Th. 1.37, 82, 143.
incomprehensible, Phld. Mus. p.54K., Plu. Nic. 11, al.
in Stoic philos., ἄληπτα, τά, things not to be made matter of choice, opp. ληπτά, Stoic. 3.34.