An adjective appearing as N. {cûn “empty”} >> cofn [kovn] or caun “empty, void” in The Etymologies of the 1930s under the root ᴹ√KUM “void” (Ety/KUM). It is not clear how of vocalized to *ou* > *au*.
Neo-Sindarin: For purposes of Neo-Sindarin, I would use ᴺS. covn “empty, void” to better fit later Sindarin orthography.
An adjective in The Etymologies of the 1930s glossed “ bowed, bow-shaped, bent” derived from primitive ᴹ✶kuʒnā under the root ᴹ√KUƷ “bow” (Ety/KUƷ).
Conceptual Development: G. cûn “bowed, bent, concave” appeared in the Gnomish Lexicon of the 1910s, along with variant forms cunwed, cuvon (GL/27).