Basic indefinite words (algo, alguien, alguno)

¿Hay alguien en casa? (Is anyone home?) ¿Tienes algo de comer? (Do you have something to eat?) When you don't need — or don't know — the specific thing or person, Spanish has a small set of words that stand in for "something," "someone" and "some."

Quick shortcut: algo → an unspecified thing. alguien → an unspecified person. alguno → an unspecified one out of a group, and it agrees in gender and number.

Algo and nada: things

Algo ("something") and its opposite nada ("nothing") work as pronouns standing in for a thing, without saying what it is.

• ¿Quieres algo de beber? (Do you want something to drink?)
• No tengo nada en la nevera. (I have nothing in the fridge.)
• Algo huele bien. (Something smells good.)

Alguien and nadie: people

Alguien ("someone") and nadie ("no one") do the same job for people.

• ¿Conoces a alguien aquí? (Do you know anyone here?)
• No vino nadie a la reunión. (No one came to the meeting.)
• Alguien llamó por teléfono. (Someone called on the phone.)

Notice alguien and nadie take the personal a when they're the direct object of a verb, just like a specific person would: ¿Conoces a alguien?, not ❌ ¿Conoces alguien?

Alguno: an unspecified one (or some) out of a group

Alguno ("some," "any," "one or another") is different from algo and alguien in one important way: it's an adjective/pronoun that agrees in gender and number — alguno, alguna, algunos, algunas — and its opposite is ninguno/ninguna ("none," "not any").

• ¿Tienes alguna pregunta? (Do you have any question?)
• Algunos estudiantes llegaron tarde. (Some students arrived late.)
• No tengo ninguna duda. (I have no doubt at all.)

Right before a masculine singular noun, alguno and ninguno shorten to algún and ningún: algún día (some day), ningún problema (no problem) — never ❌ alguno día or ❌ ninguno problema. This shortening pattern (called apocopation) shows up with a handful of other common words too, and has its own dedicated lesson.

A note on nada, nadie and ninguno with no

You've probably noticed nada, nadie and ninguno pairing with no in several examples above (No tengo nada, No vino nadie). Spanish generally needs no before the verb whenever one of these negative words comes after it — the full rules for combining them (and words like nunca and tampoco) have their own dedicated lesson. For now, it's enough to recognize algo/alguien/alguno as the "some" side and nada/nadie/ninguno as the "none" side of the same three ideas.

Common mistakes

• ❌ ¿Conoces alguien aquí? → ✅ ¿Conoces a alguien aquí? (a person, even an unspecified one, needs the personal a)
• ❌ No tengo alguna pregunta. → ✅ No tengo ninguna pregunta. (a negative sentence needs ninguna, not alguna)
• ❌ Alguno día iré a España. → ✅ Algún día iré a España. (alguno shortens to algún before a masculine singular noun)
• ❌ ¿Tienes algo pregunta? → ✅ ¿Tienes alguna pregunta? (a countable thing like "a question" needs alguna, which agrees with it — not the invariable algo)

Quick check

Choose algo, alguien, or the correct form of alguno:

1. ¿Hay ___ en la cocina? (asking if there's a person there)
2. ¿Tienes ___ amigo en Madrid?
3. Quiero comer ___ dulce.
4. ¿Necesitas ___ ayuda?

Key takeaways

• Algo (something) / nada (nothing) stand in for an unspecified thing.
• Alguien (someone) / nadie (no one) stand in for an unspecified person, and take the personal a as a direct object: ¿Conoces a alguien?
• Alguno (some/any) / ninguno (none) agree in gender and number with what they refer to, and shorten to algún/ningún right before a masculine singular noun.
• Nada, nadie and ninguno need no before the verb when they come after the verb (No vino nadie), but not when they come before it (Nadie vino) — the full rules for that live in their own lesson.