# The indefinite article: un, una, unos, unas

> id: grammar.articles.indefinite-forms · category: grammar · depth: standard · levels: A1 · review: internally_reviewed

**Summary.** Un libro, una casa; plural unos/unas means 'some' or 'a few': unos amigos, unas tres horas (approximation).

The indefinite article ('a/an', and in the plural 'some') has four forms agreeing in gender and number: un libro, una casa, unos libros, unas casas. Un/una introduce something not yet identified: hay un mensaje para ti, necesito una respuesta.

The plurals unos/unas mean 'some' or 'a few' (unos amigos, unas ideas), and before a number they mean 'about, around': unas veinte personas, unos tres días — a handy way to approximate.

The same sound rule as el agua applies: before a feminine noun starting with stressed a-/ha-, un is used instead of una — un águila, un alma, un arma — while the noun stays feminine (un águila herida).

## Examples
- Necesito una respuesta hoy. — I need an answer today.
- Llegaron unos treinta invitados. — About thirty guests arrived.
- Vinieron unas cien personas y cada una trajo un regalo. — About a hundred people came, and each one brought a gift.

Related: grammar.articles.indefinite-uses, grammar.articles.el-with-feminine-nouns

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