It is common to hear the words gender and number used together when contemplating a noun. The gender of the noun indicates whether the noun is masculine or feminine. The number of the noun indicates whether the noun is singular or plural. You will learn to identify the word libro as a singular, masculine noun, and how to make the plural version of this and all other nouns.
Before you learn how to make a noun plural, however, it's necessary to learn how to pluralize the definite and indefinite articles. A plural noun will have a plural version of the article in front of it. Comparatively, the definite article in English is the same regardless of whether the noun that follows is singular or plural.
Plural forms of definite articles
The Spanish definite article ( el and la, the) has a plural version of both its feminine and masculine forms. Therefore, the definite article has four forms in Spanish. The plural of el is los and the plural of la is las.
Plural forms of indefinite articles
The indefinite articles in Spanish are un (a) and una (an). These are only used in front of a singular noun. When a plural noun requires an indefinite article in English, the word some is used as the plural of a or an. In Spanish, there is a feminine and masculine version of the singular indefinite article, and also a feminine and masculine version of the plural indefinite article.
Plural forms of nouns
There are very simple rules to follow when creating the plural version of a noun. If a noun ends in any vowel, simply add – s to create the plural form.
If a noun ends in any consonant (including y), add –es to create the plural form.
When z is followed by e, change the z to c when forming the plural. This means that any word ending in – z will become –ces in its plural form.
Spanish uses the plural version of the masculine noun to represent a couple of mixed gender. For example:
Plural forms and accent marks
A word ending in any consonant other than n or s will be stressed on the last syllable. A word that ends in a vowel, an n, or an s will be stressed on the next‐to‐last syllable. Because in Spanish the plural form of a word would be stressed on the same syllable as the singular form, it is sometimes necessary to add or remove an accent mark when the plural version adds an entire syllable, such as –es.
If you add –es to a word that had an accent mark on the last syllable, the accent mark is eliminated.
Other words that didn't have an accent before the –es was added will require an accent in their plural form.
A noun that ends in –s will remain the same in its plural form (only the article will change) unless there is an accented vowel in front of the –s. If there is an accented vowel in front of the –s, you will add –es and drop the accent to create the plural form. This rule is important to remember with compound nouns because they usually end in –s and usually have the same form for singular and plural.