Locative

As Paul says, it is really perfectly gratuitous ("es ist im grunde reine willkur") to call the case we have in German (and Old English) a dative, for besides the functions of the dative it fulfils the functions of the old locative, ablative, and instrumental.

a locative adjective

the locative case of a noun

Brian: Ah. Ah, dative, sir! Ahh! No, not dative! Not the dative, sir! No! Ah! Oh, the… accusative! Accusative! Ah! Domum, sir! Ad domum! Ah! Oooh! Ah! Centurion: Except that domus takes the…? Brian: The locative, sir! Centurion: Which is…?!