_The Third Declension._
Genitive singular #-is#, genitive plural #-um#.
467. Consonant stems are mostly substantive, and include both gender
words and neuters.
Comparatives and a few other words are adjective. For the gender of
substantives, see 570.
468. The nominative of consonant stems ends in #-s# (or #-x#); or in
#-n# (#-ō#), #-l#, #-r#, or #-s# of the stem, rarely in #-c# or #-t#.
469. Most consonant stems have one syllable less in the nominative than
in the genitive.
Such words are called _Imparisyllabic_ words or _Imparisyllables_: as,
nominative #rēx#, _king_, one syllable; genitive #rēgis#, _of a king_,
two syllables.
470. Many consonant stems have a double form: one form used in the
nominative singular (neuters have this form in the accusative also),
another form in the other cases: as,
#iūdex#, _juror_, stem of nominative #iūdec-# (136, 2), of other cases
#iūdic-#; #flāmen# (103, _a_), _special priest_, #flāmin-# (103, _a_);
#virgō#, _maid_, #virgin-# (105, _g_); #auceps# (107, _d_), _fowler_,
#aucup-# (104, _c_); #ebur# (107, _c_), _ivory_, #ebor-#; #genus#,
_race_, #gener-# (145; 107, _c_); #trīstius# (346), _sadder_,
#trīstiōr-# (346); #corpus# (107, _c_), _body_, #corpor-# (105, _i_);
#pater# (135, 2), _father_, #patr-#. In such instances the stem of the
oblique cases is taken for brevity to represent both forms of the stem.