A noun appearing as (archaic) G. †bedhril “wife” in the Gnomish Lexicon of the 1910s, replaced in ordinary speech by G. bess (GL/22). It is a combination of the early root ᴱ√Beđ that was the basis for marriage words and the feminine agental suffix G. -(r)il (GL/22).

Neo-Sindarin: I would adapt this into Neo-Sindarin as ᴺS. bethril “spouse (f.)”, a combination of the later root ᴹ√BES “wed” and the same agental suffix, where sr became thr.