Indefinite Articles: un, una, unos, unas

Level: A1. An indefinite article is the word for “a” or “an” — the one you use for something not yet specific or mentioned for the first time. Where English has “a / an” and “some”, Spanish has four forms, because the article must match the noun’s gender (masculine or feminine) and number (singular or plural).

The rule

Pick the article from a simple grid. Gender is the masculine/feminine label every Spanish noun carries; number is singular versus plural.

• un — masculine singular → un libro (a book)
• una — feminine singular → una casa (a house)
• unos — masculine plural → unos libros (some books)
• unas — feminine plural → unas casas (some houses)

The article sits before the noun and copies its gender and number. The singulars mean “a / an”; the plurals mean “some” or “a few”. Because the article carries the gender, the safest habit is to learn every noun with its article.

The four forms

Dropping the article after ser

Spanish normally omits the indefinite article after the verb ser (“to be”) when you state a profession, nationality or religion on its own:

• Soy profesor. (I am a teacher.)
• Ella es médica. (She is a doctor.)
• Somos estudiantes. (We are students.)

But you keep the article as soon as the noun is described by an adjective:

• Soy un buen profesor. (I am a good teacher.)
• Es una médica excelente. (She is an excellent doctor.)

The un águila rule

A feminine noun that begins with a stressed a- or ha- takes un in the singular, purely so the two “a” sounds do not clash: un águila (an eagle), un hacha (an axe), un aula (a classroom).

The noun stays feminine, so:

• Adjectives keep the feminine form: un águila blanca (a white eagle).
• The plural goes back to unas: unas águilas, unas hachas.
• If the a- is not stressed, use the normal una: una amiga (a friend).

When to use unos and unas

• “Some / a few”: Compré unas manzanas. (I bought some apples.)
• “About” before a number: Hay unos veinte euros. (There are about twenty euros.)
• Paired body parts or objects: unas gafas (a pair of glasses), unas tijeras (a pair of scissors).

Often, where English says a bare plural, Spanish simply drops the article: Compré manzanas (I bought apples) is just as natural as Compré unas manzanas.

How to say it

Spanish spelling is regular, so once you know these sounds you can read the forms aloud:

Example sentences

Each sentence was written for this lesson (not copied from a third-party corpus).

1. Tengo un libro.
   I have a book.
2. Es una casa grande.
   It is a big house.
3. Compré unos libros.
   I bought some books.
4. Vi unas flores bonitas.
   I saw some pretty flowers.
5. Hay un perro en el jardín.
   There is a dog in the garden.
6. Quiero una manzana.
   I want an apple.
7. Soy profesor.
   I am a teacher.
   no article after ser + bare profession
8. Soy un buen profesor.
   I am a good teacher.
   article returns with an adjective
9. Ella es médica.
   She is a doctor.
10. Un águila vuela alto.
    An eagle flies high.
    feminine, but un before stressed a-
11. Unas águilas descansan en el árbol.
    Some eagles are resting in the tree.
    plural goes back to unas
12. Necesito unas gafas nuevas.
    I need a new pair of glasses.
13. Hay unos veinte estudiantes.
    There are about twenty students.
    unos = about before a number
14. Me dio un consejo.
    He gave me a piece of advice.
15. Es un día bonito.
    It is a nice day.
16. Tengo unas preguntas.
    I have some questions.

Common mistakes

• ❌ Soy un profesor → ✅ Soy profesor. Drop the article after ser with a bare profession.
• ❌ una águila → ✅ un águila. A feminine noun with a stressed initial a- takes un in the singular.
• ❌ un águila blanco → ✅ un águila blanca. The noun is feminine, so the adjective stays feminine.
• ❌ unos aguas → ✅ unas aguas. The plural of these feminine nouns returns to unas.
• ❌ un casa → ✅ una casa. casa is feminine, so the article is una.

A short conversation

— ¿Tienes un bolígrafo? (Do you have a pen?) — Sí, tengo unos bolígrafos en la mochila. (Yes, I have some pens in the backpack.) — ¿A qué te dedicas? (What do you do?) — Soy ingeniera. Trabajo en una empresa pequeña. (I’m an engineer. I work at a small company.)

Notice un bolígrafo (a pen), unos bolígrafos (some pens), the dropped article in soy ingeniera, and una empresa once there is a noun to count.

Usage notes

• No article after bare profession. The rule covers ser + profession, nationality (es español) and religion (es budista). Add the article only with a describing adjective.
• Only the stressed a- triggers un. un águila works because the stress is on the first a-; una amiga keeps una because the a- is unstressed.
• Plural often dropped. Spanish frequently leaves out unos/unas before a plain plural: Hay flores en la mesa (There are flowers on the table).
• Register. The choice of un, una, unos, unas is standard across Spain and Latin America; it never changes by formality, only by the noun’s gender and number.

Compared with…

• Definite articles (el, la, los, las) mean “the” and point to something specific or already known, while un, una, unos, unas introduce something new or not yet identified. Compare Quiero el libro (I want the book — a specific one) with Quiero un libro (I want a book — any book). See Definite Articles: el, la, los, las.
• Noun gender decides whether you use the masculine or feminine form; how a noun’s gender is worked out is covered in Noun Gender in Spanish.
• Plurals (unos, unas) follow the plural of the noun itself; see Making Nouns Plural.

Quick recap before the quiz.

Practice

Practice

Indefinite article practice

Try each one, then press Check. No sign-up, nothing is sent anywhere — it all runs in your browser.

1 ___ casa (a house, feminine singular)

un una unos unas

Check

Show answer

una — Feminine singular uses una: una casa.

2 ___ libros (some books, masculine plural)

un una unos unas

Check

Show answer

unos — Masculine plural uses unos: unos libros.

3 Fill the blank after ser: Soy ____ profesor paciente.

Check

Hint: There is an adjective (paciente).

Show answer

un — With an adjective, the article returns: soy un profesor paciente.

4 Fill the blank with the right article: Veo ____ águila (feminine, stressed a-).

Check

Hint: Stressed initial a-.

Show answer

un — A stressed initial a- makes a feminine noun take un in the singular: un águila.

5 Match each noun with its article.

• ___ perro Match for ___ perro — choose — ununaunasunos
• ___ casa Match for ___ casa — choose — ununaunasunos
• ___ flores Match for ___ flores — choose — ununaunasunos
• ___ libros Match for ___ libros — choose — ununaunasunos

Check

Show answer

• ___ perro → un
• ___ casa → una
• ___ flores → unas
• ___ libros → unos

un perro (m. sing), una casa (f. sing), unas flores (f. pl), unos libros (m. pl).

Quiz

Check yourself

Spanish indefinite articles

12 questions · pick an answer and you'll see straight away if it's right.

0/12 0 answered

1. 1___ libro (a book)

   A una B un C unos D unas
   Show answer

   un — Masculine singular: un libro.

2. 2___ casa (a house)

   A un B una C unos D unas
   Show answer

   una — Feminine singular: una casa.

3. 3___ libros (some books)

   A un B una C unos D unas
   Show answer

   unos — Masculine plural: unos libros.

4. 4___ casas (some houses)

   A un B una C unos D unas
   Show answer

   unas — Feminine plural: unas casas.

5. 5Which is correct: 'I am a teacher'?

   A Soy un profesor B Soy profesor C Soy una profesor D Soy unos profesor
   Show answer

   Soy profesor — Drop the article after ser with a bare profession: Soy profesor.

6. 6Add an adjective: 'I am a good teacher' is…

   A Soy buen profesor B Soy un buen profesor C Soy una buen profesor D Soy profesor bueno un
   Show answer

   Soy un buen profesor — The article returns with an adjective: Soy un buen profesor.

7. 7Which is correct for 'an eagle'?

   A una águila B un águila C unos águila D la águila
   Show answer

   un águila — A stressed initial a- makes a feminine noun take un in the singular: un águila.

8. 8The plural of 'un águila' is…

   A unos águilas B un águilas C unas águilas D una águilas
   Show answer

   unas águilas — The noun is feminine, so the plural is unas águilas.

9. 9Which is correct?

   A un águila blanco B un águila blanca C una águila blanco D unos águila blanca
   Show answer

   un águila blanca — águila takes un for sound but stays feminine, so the adjective is blanca.

10. 10'There are about twenty euros' is…

    A Hay veinte euros B Hay unos veinte euros C Hay unas veinte euros D Hay un veinte euros
    Show answer

    Hay unos veinte euros — unos before a number means 'about': unos veinte euros.

11. 11The feminine plural indefinite article is ____
    Check
    Show answer

    unas — Feminine plural: unas.

12. 12How do un, una, unos, unas differ from el, la, los, las?

    A They mean 'the' (specific) B They introduce something new or not specific ('a / some') C They never change D They are only for plurals
    Show answer

    They introduce something new or not specific ('a / some') — Indefinite articles introduce something new or unspecified; definite articles point to something known.

Recap cheat-sheet

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