From the scholia to Homer, Odyssey 1.10, where the headword occurs. The adverb a)mo/qen is a Homeric form of poqen, from a(mo/s (B) in LSJ. The root is *sm- meaning "some"; there is uncertainty whether it should be written with smooth breathing (Aeolic or Ionic) or rough breathing (Attic). See LSJ at web address 1 and web address 2.