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!
tum
noun. hollow
tumli
noun. dale
tump
noun. shed
A noun appearing as G. tump “shed” in the Gnomish Lexicon of the 1910s (GL/71), clearly a cognate to ᴱQ. tumpo “shed, barn” which was derived from either ᴱ√TṂPṂ or ᴱ√TUPU (QL/93, 95).
Neo-Sindarin: Since √TUP “cover” survived in Tolkien’s later writings, I think this word can be salvaged as ᴺS. tump “shed”, though it does conflict with [N.] tump “hump”.
tumla-
verb. to excavate, hollow out
tumbol
adjective. valley-like, hollow, excavated
tumladin
place name. Valley of Smoothness
um
adjective. lowlying
tûm
noun. valley
bada-
verb. to build
cub
adjective. hollow
dolc
adjective. deep
dûl
adjective. hollow
nal
noun. dale, vale
A word in the Gnomish Lexicon of the 1910s glossed “dale, vale”, most likely a derivative of the root ᴱ√NḶĐḶ as suggested by Christopher Tolkien (GL/59; LT1A/Murmenalda).
rothrin
adjective. hollow
tub-
verb. to cover
A noun in the Gnomish Lexicon of the 1910s glossed “a dale” (GL/72), probably a derivative of the early root ᴱ√TUM(B)U as suggested by Christopher Tolkien (LT1A/Tombo; QL/95).