Same entry in ps.-Zonaras; similar one, according to Adler, in the Ambrosian Lexicon.
The headword (again under epsilon 2961 and kappa 1050) is a poetic variant of e)rh=mos: see LSJ s.v. The glossing here can hardly be an all-purpose definition of it; rather, something generated by a particular passage or type of passage where this adjective is used of such a geographical feature (as opposed to e.g. night).