Indefinite Articles: un, uno, una, un'

English has one indefinite article that splits into two surface forms: a before consonants, an before vowels. Italian has one indefinite article that splits into four surface forms: un, uno, una, un'. The choice among them is governed by the same phonotactic logic as the definite article — the gender of the noun and the first sound of the word that follows. There is also a critical orthographic distinction (the apostrophe on un' vs no apostrophe on un) that is the single clearest gender marker in written Italian.

This page is the deep-dive on un / uno / una / un'. By the end, you should be producing the right form automatically and never confusing un amico (m.) with un'amica (f.).

1. The complete table

Five cells, four distinct surface forms — because the masculine "before consonant" and "before vowel" cases are both un.

The crucial observation: un and un' are NOT the same form. Un is the unmodified masculine indefinite article — the apostrophe-less form is just the way un is written. Un' is what happens when feminine una elides before a vowel. Same letters on the page, opposite gender.

2. The masculine indefinite: un vs uno

2.1 un — the default

Use un before any masculine noun (or adjective) that begins with most consonants or any vowel. The form does not change when crossing the consonant/vowel boundary, and there is no apostrophe in either case.

2.2 uno — the special-cluster case

The masculine uno appears in exactly the same contexts where the definite article uses lo: before words starting with s + consonant, z, gn, ps, pn, x, or y.

3. The feminine indefinite: una vs un'

3.1 una — before any consonant

Use una before any feminine noun (or adjective) that begins with a consonant. There is no equivalent of the uno complication on the feminine side; una covers all consonant contexts, plain and cluster alike.

Note: feminine una studentessa and una zebra keep una (no special form), where the masculine takes uno for parallel words.

3.2 un' — before a vowel (with apostrophe)

When the following word begins with a vowel, una elides to un'. The apostrophe is mandatory in standard written Italian.

4. The critical orthographic distinction

This is the single most important written-Italian rule on this page:

un amico = masculine "a friend" — no apostrophe. un'amica = feminine "a friend" — apostrophe required.

These are not interchangeable. Writing un'amico (with apostrophe, but for the masculine word) is a textbook learner error that an Italian reader spots immediately. Writing una amica (without elision, before a vowel) looks similarly wrong — the elision is mandatory in standard Italian.

In speech, both are pronounced /unami:ka/ or /unami:ko/ — the apostrophe is purely a written distinction. But Italians, when reading, parse the gender from the apostrophe instantly.

4.1 Why the asymmetry?

Why does the feminine elide but the masculine doesn't? Two reasons.

First, una ends in a vowel; placing it before another vowel creates a hiatus (vowel-vowel) that Italian phonology prefers to avoid. Hence una + amica → un'amica, a single phonological unit.

Second, un already ends in a consonant. There is no hiatus to resolve — un amico is /unami:ko/ with no awkward sequence. Italian doesn't elide un because there's nothing to elide.

Historically, masculine un is itself a clipped form of uno (which descends from Latin unus); the final -o has been dropped already. Adding an apostrophe to mark a further "elision" that didn't actually happen would be redundant.

The asymmetry is consistent across the rest of the language: when a vowel-final word meets another vowel, you may see elision (with apostrophe). When a consonant-final word meets a vowel, no elision happens.

5. The same noun in masculine and feminine

Many nouns have masculine and feminine variants. Pairing them is one of the best drills for the un / un' distinction.

The last example is striking: artista is invariable in spelling between masculine and feminine. The only thing that tells the reader whether it's a male or female artist is the article: un artista (m.) vs un'artista (f.). Drop the apostrophe and you've changed the gender.

6. Position rules with adjectives

Like the definite article, the indefinite article matches the first sound after itself. If an adjective precedes the noun, the article reflects the adjective's opening sound.

The pair un altro vs un'altra is one of the most useful real-life drills for the apostrophe distinction.

7. There is no plural indefinite article

This is one of the biggest structural differences between Italian and English at the article level. English has "a" (singular) and "some" (plural indefinite). Italian's indefinite article exists only in the singular. There is no uni or une.

To express "some" in the plural, you have three options:

7.1 Partitive article — most common

Use dei, degli, delle (covered in detail in Partitive Articles).

7.2 Bare noun — for generic statements

When the meaning is generic ("books in general") rather than a specific indefinite quantity, the noun appears bare with no article at all.

7.3 Indefinite quantifier — slightly more emphatic

The quantifier alcuni / alcune ("some, a few") works like a plural indefinite article and is slightly more emphatic than the partitive.

The single-form indefinite qualche + singular noun (with plural meaning!) is another option:

8. The indefinite article also means "one"

Italian uno / una is identical to the cardinal number "one" (more on this in numbers/cardinals). Context disambiguates:

In the first sentence, un means "exactly one" because of the contrast with due. In the second, it just means "a / an." The form is the same; the listener gets the meaning from context.

9. The indefinite article in negative sentences

Italian usually drops the indefinite article in negative sentences when expressing absolute non-existence:

Both are heard, but the bare-noun version is slightly more idiomatic when the meaning is "I lack X entirely."

In contrast, when the indefinite article means "any" (one), it stays:

10. Common mistakes

11. Quick reference card

Drill this card until you can produce un / uno / una / un' without thinking. Once the indefinite is automatic, you can move on to Partitive Articles, which build on the same gender + phonotactic logic to express "some" and "any."