Early Primitive Elvish
piẇi
root. *fat
faƀa
root. *fat
lara
root. *fat
fava Reconstructed
root. *fat
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
A root in the Qenya Lexicon of the 1910s appearing as ᴱ√FABA, but according to the editors the B was crossed indicating the actual root was ᴱ√FAɃA which Tolkien generally represented as ✱ᴱ√FAVA (QL/36). Its derivatives had to do with “fat” such as ᴱQ. famba “belly, fat body” and ᴱQ. fauka “fat, large”. Similar words appear in the contemporaneous Gnomish Lexicon, such as G. fam “fat belly, paunch” and G. fabwed “corpulent” (GL/34). There are no signs of this root in Tolkien’s later writing.