Iliad 1.419 says
τοῦτο δέ τοι ἐρέουσα ἔπος Διὶ τερπικεραύνῳ
LSJ (in its various forms) says it's τερπι+κέραυνος -- delighting in thunder, and I know the κεραυνός part but what's τερπι? I can't find anything on it. Does it ever appear elsewhere, by itself or as a prefix?