αὐτοπροθύμως
From LSJ
ἐπεὰν νῶτον ὑὸς δελεάσῃ περὶ ἄγκιστρον, μετιεῖ ἐς μέσον τὸν ποταμόν, ὁ κροκόδειλος ἵεται κατὰ τὴν φωνήν, ἐντυχὼν δὲ τῷ νώτῳ καταπίνει → when he has baited a hog's back onto a hook, he throws it into the middle of the river, ... the crocodile lunges toward the voice of a squealing piglet, and having come upon the hogback, swallows it
English (LSJ)
[ῡ], Adv. A voluntarily, EM173.8.
Greek (Liddell-Scott)
αὐτοπροθύμως: ἐπίρρ. ἐξ οἰκείας προθυμίας, λίαν προθύμως, Ἐτυμ. Μ. 173. 8.
Spanish (DGE)
voluntariamente, EM 173.8G.