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!

Gnomish

gwelc

noun. bubble

A noun appearing as G. gwelc “bubble” in the Gnomish Lexicon of the 1910s (GL/44). It is clearly based on the early root {ᴱ√WELE >>} ᴱ√GWELE from the contemporaneous Qenya Lexicon (QL/103).

Neo-Sindarin: Since we have no better “bubble” words, I would adapt this as ᴺS. gwelch “bubble” for purposes of Neo-Sindarin, but assume it is derived from a Neo-Root ᴺ√WEL so that it retains the initial w, and with the usual sound Sindarin change of ancient lk to lch.