Frór's name is Old Norse in form, but does not carry an obvious meaning, and it seems quite plausible that Tolkien simply designed the name to mirror that of his important elder brother Thrór. Alternatively, the name is just conceivably based on Old Norse froðr, 'wise' (the Old Norse equivalent of Old English fród in the Hobbit-name 'Frodo'). This is, however, something of a linguistic stretch, and 'wise' seems rather odd choice of name for a Dwarf who died while still a youth, at least in Dwarf terms.