nouns and plurals of nouns

As a general rule, most nouns ending in o are masculine and those ending in a are feminine, but there are exceptions.

a. Feminine nouns such as agua, álgebra, and álguila, nouns with a stressed a, are preceded by the masculine el instead of the feminine la in order to avoid the ackward sound of la ... a.

b. Nouns ending in -ie, -ad, and -ud are always feminine.
Ex: la bondad, la libertad, la juventud, la universidad, la serie

c. Nouns ending in -ción , -sion and -umbre are always feminine.
Ex: la acción (action), la revolución (revolution), la cumbre (peak), la misión (mission)

d. Letters of the alphabet, sicknesses, islands and provinces are feminine.
Ex: la fiebre (fever), la Isla de Pinos, (the Isle of Pines (Cuba)), la hache (h)

e. Nouns referring to persons and animals can be masculine or feminine.
Ex: el novio (boyfriend, bridegroom); la novia (girlfriend, bride)
el primo (cousin); la prima (cousin)
el señor (gentleman, Mr.); la señora (lady, Mrs.)
el caballo (horse); la yegua (mare)

f. Nouns referring to a person's profession or social position often end in -ista, -ante, or -ente. These nouns do not change according to gender. The difference in gender is indicated by the masculine or feminine definite article.
Ex: el estudiante, la estudiante (student)
el artista, la artista (artist, performer)
el poéta, la poéta (poet)
el orden, la orden (order)

g. Nouns referring to numbers, days of the week, musical notes, cardinal points, conmpound words, names of trees, rivers, lakes, mountains, straits, and seas are masculine as well as nouns ending in -aje.
Ex: el garaje, el naranjo, el siete, el norte, el do, el lunes, el paraguas, el Canal de Panama, el Caribe

h. Some nouns that end in -ma are masculine.
Ex: el tema (subject), el idioma (language), el problema (problem).
Plural of Nouns
The plural of a noun is formed by adding either -s or -es to the noun. The formation of the plural can affect the accenting and spelling of the word.

Add -s to nouns ending in a vowel to form the plural.
Singular			Plural
el gato			los gatos
la silla			las sillas

Add -es to nounes ending in a consonant to form the plural.
el árbol			los árbol es
la verdad			las verdades
el mes			los meses

If a nouns ends in -z, change the -z to -c and add -es to form the plural.
la voz			las voces
la luz			las luces
el lápiz			los lápices

The masculine plural form of Spanish nouns can include the female members of a group as well as the males.
los hijos	sons	son and daughter	sons and daughters
los señores	gentelmen	Mr. and Mrs.
los padres	fathers	father and mother	fathers and mothers

Plural of Nouns