1. to rejoice over, exult over , mostly of malignant joy, with dative, (Sophocles Tragicus); absolute, (Aristophanes Comicus), etc.

2. rarely in good sense, to rejoice in another's joy , with accusative, σὲ μὲν εὖ πράσσοντ᾽ ἐπιχαίρω (Sophocles Tragicus) (ML)