thanklessness
From LSJ
πολλὰ γάρ σε θεσπἰζονθ' ὁρῶ κοὐ ψευδόφημα (Sophocles' Oedipus Coloneus 1516f.) → For I see in you much prophecy, and nothing false
English > Greek (Woodhouse)
substantive
ingratitude: P. ἀχαριστία, ἡ.
forgetfulness: P. and V. λήθη, ἡ.
odiousness: use P. τὸ ἐπίφθονον.