A noun in the Gnomish Lexicon of the 1910s glossed “bark, skin, peel”, related to the verb G. daf- “strip, flay, peel skin” (GL/29). In Gnomish Lexicon Slips modifying that document, Tolkien instead gave {daus >>} dâf “bark” (PE13/112).
Gnomish
dâ
adjective. high
dân
noun. day
dâd
noun. grandfather
dâf
noun. bark
dana
noun. day (24 hours)
danuin
masculine name. Day
dafros
noun. bark, skin, peel
padhwen
noun. bark
A noun for “bark” in the Gnomish Lexicon of the 1910s (GL/63), apparently based on the early root ᴱ√PARA [PAÐA?] which might mean “peel” (QL/72).
mactha-
verb. to slay, kill
târ
noun. horn
nâd
noun. grandfather
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).