revengeful
From LSJ
πάντα χωρεῖ καὶ οὐδὲν μένει καὶ δὶς ἐς τὸν αὐτὸν ποταμὸν οὐκ ἂν ἐμβαίης → all things move and nothing remains still, and you cannot step twice into the same stream
English > Greek (Woodhouse)
adjective
unforgetting: P. and V. μνήμων; see implacable.
be revengeful, v.: Ar. and P. μνησικακεῖν.