Probably from shemen; a fat-field -- desolate place.
see HEBREW shemen
H820. ashmannim
אַשְׁמַנִּים (elative, Ges§§ 85b, 133a; on נּ see Id.§§ 20a, 93ee) apparently
noun [masculine] plural ׳בָּא כַּמֵּתִים Isaiah 59:10 perhaps: (we are) among the stout (RV lusty) like dead men, compare Di-Kit; or abstract in (actual) vigour (Buhl) > AV (after JosKi from אָשַׁם Hosea 14:1 'be desolate'') in desolate places (other conjectures see (CheHpt Marti).