Ἀχιλλεύς
From LSJ
ἐξ ὀνύχων λέοντα τεκμαίρεσθαι → judge by the claws, judge by a slight but characteristic mark, small traits give the clue to the character of a person, deduce something from a small indication, identify a lion from its claws
English (LSJ)
Ep. also Ἀχιλεύς, gen. Ἀχιλλέως (either quadrisyll. or trisyll., as the metre requires, cf. S.Ph.4,50 with 57,364): acc. Ἀχιλλέᾱ ib.331,358, voc. Ἀχιλλεῦ: Ep. gen. Ἀχιλλῆος, etc.:— Achilles. II the fallacy vulgarly called Achilles and the Tortoise', invented by Zeno of Elea, Arist.Ph.239b14, D.L.9.29.