ὁ/ἡ ὄνος, –ου – a donkey
ὁ ὄνος μάλα χρήσιμόν ἐστι ζῷον τοῖς ἀνθρώποις· φέρει γὰρ βαρύτατα φορτία· ὑπάρχει δὲ καὶ κάλλιστον διήγημα τοῦ Λουκιανοῦ περὶ ἀνθρώπου ὃς ὄνος γίγνεται· δύνασθε δ’ἀναγνῶναι τοῦτο τὸ διήγημα ἐνταῦθα· http://lucianofsamosata.info/downloads/lucians_the_ass_-_hayes_and_nimis_oct_2012.pdf
The donkey is an animal that is pretty useful for humans because it carries very heavy loads. There exists also a really beautiful story by Lucian about a man who turned into a donkey. You can read this story here: http://lucianofsamosata.info/downloads/lucians_the_ass_-_hayes_and_nimis_oct_2012.pdf