Forming Plurals
Conveniently enough, in Spanish a noun is made plural by adding an -s or -es, just as you do in English. If a noun ends in a vowel, use the -s ending:
carta (letter) |
cartas (letters) |
abuelo (grandfather) |
abuelos (grandfathers) |
guante (glove) |
guantes (gloves) |
Nouns ending in a consonant take on -es to form a plural:
comedor (dining room) |
comedores (dining rooms) |
habilidad (ability) |
habilidades (abilities) |
matón (killer) |
matones (killers) |
As you can see from the example of matón/matones, making a noun plural may affect the use of the accent mark. Remember, words ending with a vowel, S, or N generally have a stressed second-to-last syllable, and exceptions must employ the accent mark to show where the stress falls. Because matón is pronounced “mah-TOHN,” and not “MAH-tohn,” the accent mark is employed to indicate correct pronunciation. However, by adding -es the syllable “ton” becomes second-to-last, thus making the accent mark unnecessary in the plural.
Spelling Modifications
It's also important to remember that adding the plural ending may affect the spelling of the word. For instance, a final Z will change to C, in order to avoid combination ZE, which does not occur in Spanish: el pez (fish), los peces (fishes).
QUESTION
If a plural noun refers to a group of both genders, which ending should be used?
Plural nouns that refer to a mixed group of both genders retain a masculine ending. For example, even if you've got one male cousin and twelve female cousins, you will refer to them collectively as los primos.
Other Exceptions
As you know, some English nouns don't have a singular and a plural form. For example, the word “elk” can be either singular or plural. The only way to know is through context. A few Spanish words behave the same way. For example, a compound word where the second part of the word is plural will retain the same ending, whether the noun is singular or plural: paraguas (umbrella, literally “for water”) is el paraguas in the singular and los paraguas in the plural.
Other nouns only exist in the singular form, even though they refer to more than one person or object. The best example is “people” or gente. Although the noun refers to multiple individuals, the form both in English and in Spanish remains singular.

