A noun for “grandfather” in the Gnomish Lexicon of the 1910s with variants G. dâd and nâd, the latter related to G. nathon “father” (GL/29, 59).

Neo-Sindarin: As we have no other attested alternatives, I would use ᴺS. dâd for “grandfather” in Neo-Sindarin, but would avoid nâd since in later writings Tolkien use naneth for “mother” (Ety/NAN).