ager (nom. sing.)

agrí (gen. sing.)

2nd decl. "r" noun

masculine

animus (nom. sing.)

animí (gen. sing.)

masculine

annus (nom. sing.)

anní (gen. sing.)

masculine

barbarus (nom. sing.)

barbarí (gen. sing.)

masculine

captívus (nom. sing.)

captíví (gen. sing.)

masculine

colónus (nom. sing.)

colóní (gen. sing.)

masculine

fílius (nom. sing.)

fílí (gen. sing)drop extra "i" here 

* notice stem is fíli

masculine

magister (nom. sing.)

magistrí (gen. sing)

2nd decl. "r" noun

masculine

puer (nom. sing.)

puerí (gen. sing.)

2nd decl. "r" noun

masculine

socius (nom. sing.)

socí (gen. sing)drop extra "i"  

*notice stem is soci

masculine

vir (nom. sing.)

virí (gen. sing.)

2nd decl. "r" noun

masculine

amícitia (nom. sing.)

amícitiae (gen. sing.)

feminine

casa (nom. sing.)

casae (gen. sing.)

feminine

céna (nom. sing.)

cénae (gen. sing.)

feminine

disciplína (nom. sing.)

disciplínae (gen. sing.)

feminine

glória (nom. sing.)

glóriae (gen. sing.)

feminine

grátia (nom. sing.)

grátiae (gen. sing.)

feminine

lingua (nom. sing.)

linguae (gen. sing.)

feminine

máteria (nom. sing.)

máteriae (gen. sing.)

feminine

patria (nom. sing.)

patriae (gen. sing.)

feminine

castra (nom. pl.)

castrorum (gen. pl.)

Always plural in form - singular in meaning

Neuter

cónsilium (nom. sing.)

cónsilí (gen. sing)drop extra "i"

*notice stem is consili

Neuter

frúmentum (nom. sing.)

frúmentí (gen. sing.)

Neuter

praemium (nom. sing.)

praemí (gen. sing)drop extra "i"

*notice stem is praemi

Neuter

signum (nom. sing.)

signí (gen. sing.)

Neuter