Possessive adjectives and pronouns used as subjects

An important difference with English is that either used alone (as pronouns) or followed by a noun (used as adjectives), they always need an article (definite or indefinite), while in English always rejects articles before a possessive adjective or pronoun.

la mia automobile è veloce = my car is fast (here my acts as an adjective for the noun car)
la loro è lenta = theirs is slow (here theirs is a pronoun, meaning their car, not mentioned)

il suo gatto prese un topo = his cat caught a mouse
anche il tuo prese un topo = also yours caught a mouse

il vostro albero è alto = your (plur.) tree is tall
il loro è basso = theirs is short

un tuo parente = a relative of yours (or one of your relatives)
uno mio = one of mine

(this last example also recalls the rule for indefinite articles used as pronouns, explained in paragraph 2.4).

Only when the possessed noun is a specific family relative the article is dropped, as in English:

mio padre è alto (not "il mio padre") = my father is tall
mia madre è giovane (not "la mia madre") = my mother is young
mio fratello è pigro (not "il mio fratello") = my brother is lazy

This will be explained again further down in the page, in a more detailed way, with further examples.

Another important difference is that while in English the gender of the possessive pronoun matches the possessor, in Italian it matches the possessed subject:

mio padre ha una bicicletta = my father has a bycicle
la sua bicicletta (sua matches bicicletta, feminine) = his bycicle (his matches father, masculine)

mia madre ha un cane = my mother has a dog
il suo cane (suo matches cane, masculine)= her dog (her matches mother, feminine)

Number too must match the possessed subjects (English possessive pronouns do not have a plural):

mio padre ha due biciclette = my father has two bycicles
le sue bicicletta (sue matches biciclette, feminine plural)

mia madre ha tre cane = my mother has three dogs
i suoi cani (suoi matches cani, masculine plural)

 

The article too matches the possessed subject (noun) for gender and number, but it matches the possessive pronoun for phonetics. If this seems difficult, focus this sample sentence:

la mia automobile è veloce = my car is fast

la is a feminine singular article, since automobile is a feminine singular noun;
mia is a feminine singular possessive pronoun, for the same noun.
Had the pronoun mia not been there, the sentence would have read:

l'automobile = the car

where the article la would have been shortened in l', phonetically matching automobile. But in the previous sentence, the the word next to the article is not the noun but mia, which has to be phonetically matched.
These are more sentences with the same situation.

 

l'occhio	the eye		il mio occhio	my eye
la casa	the house		la tua casa	your house (singular)
lo studio	the study		il loro studio	their study
un'amica	a friend (feminine)		una mia amica	a friend of mine (feminine)

The definite article is omitted only when nouns indicate a family relationship:

padre = father; madre = mother;
fratello = brother; sorella = sister;
marito = husband; moglie = wife;
figlio = son; figlia = daughter;
zio = uncle; zia = aunt;
nonno = grand-father; nonna = grand-mother;
nipote (both sexes) = nephew / niece / grand-son / grand-daughter;
suocero = father-in-law; suocera = mother -in-law;
genero = son-in-law; nuora = daughter-in-law.

Therefore:

il mio amico = my friend (note the use of the article il)
.......BUT
mio padre = my father (without an article)

la madre del mio amico = my friend's mother (with compound preposition del = di + il)
.......BUT
l'amico di mia madre = my mother's friend (with simple preposition di)

regalerò un libro al mio amico = I shall give a book to my friend (preposition al = a + il)
.......BUT
regalerò un libro a mio zio = I shall give a book to my uncle (with simple preposition a)

If the noun is plural, it requires an article in any case:

mia sorella = my sister (without an article)
.......BUT
le mie sorelle = my sisters (with an article)

la casa di mio nonno = my grandfather's home (with simple preposition di)
.......BUT
la casa dei miei nonni = my grandparents's home (with compound preposition dei)

comprerò un regalo per tuo genero = I will buy a gift for your son-in-law (without an article)
.......BUT
comprerò un regalo per i tuoi generi = I will buy a gift for your sons-in-law (with an article)
(notice that preposition per does not form compounds with articles)

 

Indefinite articles, instead, are always used, also for relatives:

mio zio = my uncle
un mio zio = an uncle of mine (or one of my uncles), with an article

mia nonna = my grand-mother
una mia nonna = one of my grand-mothers, with an article

Notice that, as for most other nouns, when a family relation name is plural, the masculine form may refer either to masculine gender only or to both genders (meaning masculine and feminine together, i.e. uncles and aunts, grand-father and grand-mother, etc.), while feminine plural only refers to feminine relatives.
Instead, when nouns describing different sexes have a different root, both nouns are actually mentioned:

zio	uncle	zia	aunt
zii	uncles or uncles and aunts	zie	aunts (only)
nonno	grand-father	nonna	grand-mother
nonni	grand-fathers or grand-parents	nonne	grand-mothers (only)
	...BUT
fratello	brother	sorella	sister
fratelli e sorelle	brothers and sisters
genero	son-in-law	nuora	daughter-in-law
generi e nuore	sons- and daughters-in-law