In this passage from Nicomachean Ethics, Aristotle uses the word ἐπιχαιρεκακία to mean:
My question is, Does ἐπιχαιρεκακία have a Latin counterpart in either Classical or Medieval ethical works?
After brief research, it appears that Latin had no equivalent of ἐπιχαιρεκακία (i.e., a single word capturing the essence of the Greek word). Rather, Thomas Aquinas (for one) translated the word ἐπιχαιρεκακία into Latin as gaudium de malo,1 which in English translates as “joy from evil (misfortune).”
In Dictionarium Latino-Græcum, a Latin-Greek dictionary composed by Charles Estienne in 1554, Estienne defined ἐπιχαιρεκακία as gaudium ex alienis malis acceptum—“joy received from another’s misfortune.”2
Aquinas, Thomas. Commentary on the Nicomachean Ethics. Trans. Litzinger, C. I. Chicago: Regnery, 1964.
Estienne, Charles. Dictionarium Latino-Græcum. Lutetia: Typographum Regium, 1554.
1 Book II, Lecture 7, Chapter 6, D’, 3., a., §329
2 p. 337