Masculine and Feminine Nouns with mute stems form the Nominative by adding s to the stem.
A labial (p) is retained before s: as, príncep-s.
A lingual (t, d) is dropped before s: as, míles (stem mílit-), cústós (stem cústód-).
A palatal (c, g) unites with s to form x: as, dux (for ¥duc-s), réx (for ¥rég-s).
a. In disyllabic stems the final syllable often shows e in the nominative and i in the stem: as, prínceps, stem príncip- (for -cap-).