Un momento or Uno momento? Which One is Right in Spanish?

In Spanish, the phrase uno momento is incorrect. Instead, un momento is used. This is because when “uno” precedes a masculine noun like el momento, it always loses the “o”.

Saying uno momento rather than un momento is one of the most common grammar mistakes I hear from people who’ve studied a little Spanish in school and forgotten a lot of it, so I thought it was worth covering thoroughly here.

To help you understand this more broadly and use it in practice, let’s look at this concept a little deeper.

Why do you say Un momento and not Uno momento?

The word uno is most often used for counting. The words un or una are used before nouns, exactly the same as we use a or an in English.

So when you’re doing math, or counting how many people are at the party, you’ll use uno, dos, tres, cuatro, cinco, etc.

But as soon as you introduce a person, place, or thing into the mix, it becomes un or una.

Since momento is a noun, and it’s masculine, you drop the o.

Same thing goes if you’re talking about a book (un libro), a keyboard (un teclado), or a microphone (un micrófono).

A book, which in Spanish is un libro (not uno libro)
Remember, we say un libro — not uno libro!

Note that Spanish doesn’t make a clear distinction between one and a/an like we do in English.

So “un libro” could be translated as one book or a book, depending on context. Same thing for feminine words: depending on the context, una casa could be translated as one house or a house.

When do you use Uno in Spanish?

Here’s a scenario where you would say uno:

“¿Dónde está el bus? Llevamos mucho tiempo esperando” [Where’s the bus? We’ve been waiting a long time”

“Mira, ahora llega uno” [Look, one’s coming now]

This is because you are saying how many — without repeating the noun (bus).

However, if you wanted to say “Look, there’s a bus coming now” you’d say

“Mira, ahora llega un bus”.

City buses
When a bus arrives, un bus llega. But if multiple arrive, unos buses llegan.

Let’s take another example:

Oye amor, ¿cuántos tenedores ya están en la mesa?” [hey honey, how many forks are already on the table?]

“Hay sólo uno” [There’s only one]

Now, what if you wanted to say “There’s only one fork”, what would you say?

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.[Seriously, guess! Fork = el tenedor]

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Answer: you’d say, “Hay sólo un tenedor

This is un tenedor. A tip to remember: it shares the same root as the verb tener (to have). And a fork helps you “have” something.

Note that in both of the sentences above, the words un or uno would typically be emphasized— as in “hay sólo uno“, or “Hay sólo un tenedor“.

How do you know when to use Un vs. Una?

Lucky for us, Spanish makes this easy. Un goes before masculine nouns (un hombre, un perro), while una goes before feminine nouns (una mujer, una casa).

Examples with un:

  • Hay un carro afuera de la casa [there’s a car outside the house]
  • Un perro está ladrando
  • El libro fue un gran éxito

Examples with una:

  • Hay una casa nueva en la esquina [there’s a new house on the corner]
  • Una de mis hijas empieza la escuela este año [one of my daughters starts school this year]
  • ¿Dónde está la salida? Hay una a la izquierda y otra a la derecha.

When do you use unos and unas?

Unos and unas are used to describe an unspecified quantity of something, in the same way as we use the word “some” or “a few” in English.

Let’s take the above nouns and make them plural:

Un bus (a bus) -> unos buses (some buses)

Un libro (a book) -> unos libros (some books)

Una casa (a house) -> unas casas (some houses)

Una silla (a chair) -> unas sillas (some chairs)

Putting it into practice!

Take 5 minutes. Look around the room you’re in now and name 5 things you see, where the quantity is one.

Use this simple sentences structure: “Hay un/una noun

For example, “Hay una silla“,Hay un lápiz“.

Connor Kane, Spanish coach

Thanks for reading! I'm Connor Kane, the Spanish coach and creator behind Breakthrough Spanish. I'm not a native Spanish speaker — which means I know exactly what it's like to learn Spanish from scratch, like you. Breakthrough Spanish helps you save time, get focused, and speak confident Spanish faster.