Statt von Substantiv spricht man auch von Dingwort, Gegenstandswort, Hauptwort, Namenwort, Nennwort oder Nomen :) Germans often say Hauptwort. Nomen or Substantiv is used by well-educated people.

'Nomen' or 'Substantiv' are both fine, although the latter is more common when speaking. Hope it helps :)