Indefinite Articles (Un/Una/Unos/Unas)

The indefinite articles in Spanish correspond to the English words a, an, and some. Like the definite articles, they must agree with the noun in both gender and number.

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The Four Indefinite Articles

	Singular	Plural
Masculine	un	unos
Feminine	una	unas

Basic Examples

Spanish	English
un libro	a book
una mesa	a table
unos libros	some books
unas mesas	some tables
un amigo	a friend (male)
una amiga	a friend (female)
unos amigos	some friends
unas amigas	some friends (female)

Tip: The indefinite article un is also the number "one" in Spanish. Context makes the meaning clear: Tengo un hermano can mean "I have a brother" or "I have one brother."

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Choosing the Correct Indefinite Article

Just like with definite articles, you need to match gender and number.

Noun	Gender	Number	Article	Full Form
perro	masculine	singular	un	un perro
perros	masculine	plural	unos	unos perros
ciudad	feminine	singular	una	una ciudad
ciudades	feminine	plural	unas	unas ciudades

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The Plural: Unos/Unas = "Some" or "A Few"

Unlike English, where "a/an" has no true plural form, Spanish unos/unas serves as the plural equivalent, meaning some, a few, or approximately.

Meaning "Some" or "A Few"

Spanish	English
Hay unos libros en la mesa.	There are some books on the table.
Tengo unas amigas en Madrid.	I have some friends in Madrid.
Compré unos zapatos.	I bought some shoes.
Vi unas películas buenas.	I saw some good films.

Meaning "Approximately"

Spanish	English
Tiene unos treinta años.	He is about thirty years old.
Hay unas veinte personas.	There are about twenty people.
Costó unos cincuenta euros.	It cost about fifty euros.

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Special Case: Feminine Nouns with Un

Just as some feminine nouns take el instead of la (when they begin with a stressed a- or ha-), the same nouns take un instead of una in the singular.

Singular	Plural	Meaning
un agua mineral	unas aguas minerales	a mineral water / some mineral waters
un águila enorme	unas águilas enormes	a huge eagle / some huge eagles
un alma bondadosa	unas almas bondadosas	a kind soul / some kind souls
un hacha afilada	unas hachas afiladas	a sharp axe / some sharp axes

Remember: These nouns are still feminine. Adjectives remain feminine:

• un agua fría (a cold water) — fría is feminine

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When to Use Indefinite Articles

1. Introducing Something New or Unknown

When you mention something for the first time or when the listener does not know which specific thing you mean.

Spanish	English
Tengo un coche.	I have a car.
Vi una película ayer.	I saw a film yesterday.
Necesito un bolígrafo.	I need a pen.

2. Describing What Something/Someone Is

Spanish	English
Es un buen libro.	It is a good book.
Madrid es una ciudad grande.	Madrid is a big city.
Es un profesor excelente.	He is an excellent teacher.

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