540. (1.) The nominative singular of gender stems in #-i-# is usually
formed by adding #-s# to the stem (422). But many gender substantives
have the nominative in #-ēs# (236, 401): as,
#amni-#, _river_, N. #amnis#; #aedi-#, _temple_, N. #aedis#; #brevi-#,
_short_, N. #brevis#. With N. #-ēs#: #nūbi-#, _cloud_, N. #nūbēs#; for
other examples, see 523.
541. Some substantives form the nominative in both these ways: as,
#vallēs# and #vallis#, _valley_, equally common; #aedis#, _temple_,
later #aedēs#; for #caedēs#, _slaughter_, #clādēs#, _disaster_, and
#mōlēs#, _pile_, #caedis#, &c., occur exceptionally.
542. A few stems in #-bri-#, #-cri-#, or #-tri-#, drop #-i-# in the
nominative. The endings #brs#, #crs#, #trs#, then change to #-ber#,
#-cer#, #-ter# (111, _b_): as, #imbrī-#, _shower_, N. #imber# (525).
543. Of gender imparisyllables, some have lost #-i-# of the stem before
#-s# in the nominative; others have originally a consonant stem in the
nominative (529-535).
Thus, #monti-#, _mountain_, and #sorti-#, _lot_, have N. #mōns# and
#sors# for an older #montis# and #sortis#; but #dēns#, _tooth_, and
#regēns#, _ruling_, have as original stems #dent-# and #regent-#.
Adjectives in #-cipiti-# have N. #-ceps# (533).
544. A few adjective stems in #-li-# or #-ri-# drop #-i-# in the
nominative without taking #-s# (536, 537): as, #vigili-#, _wide-awake_,
N. #vigil#; #pari-#, _equal_, N. #pār#; so also #Arar# and #Liger#.
Three substantives in #-ri-# for #-si-# likewise drop #-i-#, and end in
the original #-s# (538): #glīri-# for #glīsi-#, _dormouse_, N. #glīs#;
#mās#, _male_; #mūs#, _mouse_.
545. For #carō#, F., _flesh_, #carnis# (Ab. #-ī#, usually #-e#, no
G. Pl.) see 135, 2. #supellēx#, F., _furniture_, #supellēctilis#
(Ab. #-ī# or #-e#, no Pl.), has the nominative formed from a different
stem from that of the other cases (401).
546. (2) Neuter stems in #-i-# have no nominative suffix, and end in
#-e# for #-i-# of the stem (107, _b_): as,
#mari-#, _sea_, N. #mare#; #brevi-#, _short_, N. #breve#. In some words,
originally neuter adjectives in #-āle# and #-āre#, the #-e# is dropped
and the #ā# shortened: as, #animāle#, _living thing_, #animal# (536);
#exemplāre# (Lucr.), _pattern_, #exemplar# (537). Some neuter adjectives
end in #-l# or #-r# (536, 537); and some ‘of one ending’ end in #-s#
(612).
547. The accusative singular of gender substantives usually has #-em#,
like consonant stems (424); but a few substantives with the nominative
in #-is# have #-im# only, and some have either #-im# or #-em#.