Articoli Indeterminativi

The indefinite article indicates an imprecise, unspecific individual or thing.
In Italian un, uno, una, un’ are used for the English article ‘a/an’, or the numeral ‘one’.

UN is used with masculine words beginning with most consonants and with vowels:
un libro - a book/one book
un aereo - a plane/one plane

UNO is used with masculine words beginning with /z/gn/pn/ps/x, or with s + consonant:
uno zaino - a rucksack
uno psicologo - a psychologist
uno specchio - a mirror

UNA is used with feminine words beginning with a consonant:
una casa - a house
una ragazza - a girl

UN’ (with apostrophe) with feminine words beginning with a vowel:
un’anatra - a duck
un’isola - an island

Indefinite articles
Masculine un/uno
Feminine una/un'