[ᴱ]*√LUB³ root. “lump”
A hypothetical root implied by the primitive word ✶lubbu “a clumsy piece or lump” appearing in both the Outline of Phonetic Development (OP1) from the 1930s and the Outline of Phonology (OP2) from the early 1950s serving to illustrate the unvoicing of double stops in Quenya: ✶lubbu > Q. luppo (PE19/45, 92).
The root may be related to earlier ᴱQ. ulumpe “camel”: although its root was given as ᴱ√ULUN(T) in the Qenya Lexicon of the 1910s, Tolkien gave ulumpe- in parenthesis beside the root, indicating it was probably an elaboration on unattested *ᴱ√LUPU (QL/97). It might also be connected to G. lub “fat, fat flesh” < ᴱ✶lūpe as well as G. lubi “corpulent” (GL/55), especially given primitive ✶slūbŭ “greasy, fat” from Common Eldarin: Noun Structure of the early 1950s (PE22/82).
Neo-Eldarin: I think it is worth positing a variant root ᴺ√LUP “hump” for Neo-Eldarin in order to salvage Early Qenya camel words.
[ᴱ]*ᴹ√LUB² root. “lump”
ᴱ✶lūpe n. “fat, fat flesh”
Reference ✧ GL/55