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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?

Thanks!

I haven't been able to figure out how to search the Perseus LSJ page for just a fragment of a word. Better yet, if there were an online page-by-page version of the whole lexicon (or either of its abridged versions) that would be wonderful...