Indefinite Articles in Spanish

Indefinite articles accompany nouns when referring to a nonspecific item. In English, we have the indefinite articles "a" and "an," which correspond to the Spanish indefinite articles un and una. Spanish also has plural indefinite articles unos and unas, which correspond to certain uses of the word "some." The indefinite articles must match the noun the modify in terms of number and gender.
singular plural
masculine un unos
feminine una unas
Necesitamos un taxi. [We need a taxi.]
Compraron unos libros nuevos la semana pasada. [They bought some new books last week.]
Hay unos pájaros en el jardín. [There are some birds in the garden.]

If a feminine singular noun starts with a stresses á, a, or ha, the masculine singular un is used rather than una, to help with pronunciation. If the noun is plural, unas is used.
un águila [an eagle] unas águilas [some eagles]
un hambre [a hunger] unas hambres [some hungers]

As you saw in the lesson on definite articles, indefinite articles follow different grammatical rules about when they should be used in English and in Spanish.

Here are the most common uses of indefinite articles:

1. In constructions following the pattern subject = noun, meaning that you are identifying what type of noun something is.
Mi hijo es un ángel. [My son is an angel.]
Una manzana es una fruta. [An apple is a fruit.]

2. To refer to an approximate amount of something.
Necesitamos unos personas más. [We need a few more people.]
Comí unos hamburguesas. [I ate a few hamburgers.]
Busco un lápiz. [I'm looking for a pencil.]
Estudiamos unos noventa minutos. [We studies about 90 minutes.]

Here are the most common situations where indefinite articles are NOT used, though English speakers tend to want to use them.

1. Describing an unknown amount
¿Hay muchachas en el equipo? [Are there any girls on the team?]
Hay huevos en este pastel? [Are there any eggs in this cake?]

2. Referring to the idea of a thing rather than a specific item. This especially occurs when discussing professions, religions, and nationalities.
Él es medico. [He's a doctor.]
Ella es católica. [She's a Catholic.]
Mis profesores son españoles. [My teachers are Spaniards.]

3. Before cierto/a, medio/a, tal(es), otro/a, or mil. Buscamos cierta calidad. [We're looking for a certain quality.]
Te llamo en media hora. [I'll call you in a half an hour.]
Tal casa no existe. [Such a house doesn't exist.]
Necesito otro papel. [I need another paper.]
Vamos a dar mil dólares. [We're going to give a thousand dollars.]

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Definite Articles in Spanish
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