A noun appearing as G. tethlas “petal” in the Gnomish Lexicon of the 1910s, a combination of G. teth “bud” and G. lass “leaf” (GL/70), the latter sometimes also used for “petal” according to Tolkien’s notes in the 1910s (GL/52).

Neo-Sindarin: For purposes of Neo-Sindarin, I would adapt this word as ᴺS. tuilas “petal” using the 1930s word [N.] tui “bud” instead of 1910s teth. However, I would use S. lass only for “leaf”, not “petal”.