Noun Gender

Note: Noun gender in Latin is grammatical, not strictly biological (though one can see traces of earlier gendered concepts), as in English. Thus, the terms are “masculine” and “feminine,” not “male” and “female.” Neuter is “ne-uter,” “not either” (masculine or feminine).

     The Romans defined gender by what kind of adjective agreed with it:
Varro (de Lingua Latina IX.41) says: itaque ea [verba] virilis dicimus non quae virum significant, sed quibus proponimus “hic” et “hi,” et sic muliebria in quibus dicere possumus “haec” aut “hae.”

Similarly, “Genera nominum sunt principalia tria, masculinum, femininum, neutrum. Masculinum est cui numero singulari casu nominativo pronomen praeponitur “hic,” ut “hic Cato.” Femininum est cui numero singulari casu nominativo pronomen praeponitur “haec,” ut “haec Iulia.” Neutrum est cui numero singulari casu nominativo pronomen praeponitur “hoc,” ut “hoc templum.” Ex his quartum genus, “commune,” nascitur . . . sunt enim communia duum generum ex masculino et feminino, ut “hic” et “haec homo” et “hic” et “haec sacerdos.” (Diomedes Ars Grammatica I, Keil I, 301)

     There are patterns as to which nouns are which gender. (See also: “Review of Noun Forms” and “Scientific Nomenclature”)

-a stem (1st Declension)
-a, -ae: feminine (first and feminine)

     *except: when it refers to a male person, e.g. nauta, agricola, poēta, incola, danīsta

-o stem (2nd Declension)
genitive, -ī

nom. -us or -er (and vir): masculine

     *except tree names are feminine

nom. -um: neuter
3rd Declension (consonant and -i stem)
genitive -is

nom. -r: masculine

     *except when it refers to a female person, e.g. feminine soror, māter

     *except neuter: iter, itineris

nom. -s, -ō, -x: feminine

Note especially these common suffixes (abstract nouns):

     -tās, -tātis

     -(t)iō, -(t)iōnis

     -tūs, -tūtis

     -tūdō, -tūdinis

     *except ignis; some -ns are masculine

neuter

     -men (gen. -minis),

     -us, -oris or -eris (e.g. tempus; opus; onus)

4th Declension (-u stem)
-us, -ūs

masculine (always if from the 4th principal part of a verb)

*except feminine: domus, manus, idūs 

*except neuter: cornu, genu 

5th Declension (-e stem)
-ēs, -eī

feminine *except: diēs is masculine, unless it refers to a set day.