Gnomish
siel
noun. granddaughter
niel
noun. granddaughter
Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!
siel
noun. granddaughter
niel
noun. granddaughter
A noun appearing as G. siel “granddaughter” in the Gnomish Lexicon of the 1910s, a feminine variant of sion “grandson” (GL/67).
Neo-Sindarin: Since there are no other attested alternatives, I would use ᴺS. siel for “granddaughter” in Neo-Sindarin, as a now-obscure modification of S. -iel “daughter”.