In short

An Italian adjective copies the gender and number of the noun it describes: un libro rosso, una borsa rossa, due borse rosse. Its normal place is after the noun, unlike English. A small group of very common adjectives goes before the noun instead, and a few of those change shape there.

The rule

Step 1 - Find the noun’s gender and number. The adjective has no gender of its own; it borrows the noun’s. Look at the noun first, then dress the adjective to match.

Step 2 - Pick the adjective’s class. There are only two.

Class 1 has four endings: -o (masculine singular), -a (feminine singular), -i (masculine plural), -e (feminine plural). Dictionary form: alto.

Class 2 has two endings: -e (both genders, singular), -i (both genders, plural). Dictionary form: grande. These adjectives do not show gender at all in the singular - only number.

Step 3 - Attach the ending. un ragazzo alto, una ragazza alta, dei ragazzi alti, delle ragazze alte. And with class 2: un ragazzo grande, una ragazza grande, dei ragazzi grandi, delle ragazze grandi.

Step 4 - Mixed groups go masculine plural. If an adjective describes a masculine noun and a feminine noun together, the ending is -i: Marco e Anna sono italiani.

Step 5 - Place it after the noun by default. This is the neutral, informative position: una macchina rossa, un film italiano, un esercizio difficile. Adjectives of colour, nationality, shape and material are effectively always post-nominal - una bandiera verde, never una verde bandiera.

Step 6 - Know the pre-nominal set. A handful of short, high-frequency adjectives normally go before the noun: bello, buono, brutto, grande, piccolo, giovane, vecchio, nuovo, bravo, lungo, breve. Before the noun they feel expected, subjective, part of the label; after the noun they carry emphasis or a real contrast.

With some of these the position changes the meaning, not just the tone:

• un grand’uomo = a great man / un uomo grande = a big (tall, large) man
• un vecchio amico = a long-standing friend / un amico vecchio = an elderly friend
• una povera donna = a poor thing, to be pitied / una donna povera = a woman with no money
• un certo risultato = a certain (some) result / un risultato certo = a sure result
• diverse persone = several people / persone diverse = different people

Step 7 - Reshape bello, buono, grande before the noun. Placed before the noun, these three shorten or follow the article pattern.

bello behaves like the definite article il / lo / la / i / gli / le: il bel libro, il bello specchio, il bell’albero, i bei libri, i begli specchi, la bella casa, le belle case. After the noun it is regular: un libro bello.

buono in the singular behaves like the indefinite article un / uno / una / un’. Ask which article the noun would take, then use the matching form: un libro -> un buon libro; uno studente -> un buono studente; una ragazza -> una buona ragazza; un’amica -> una buon’amica (though una buona amica is more common today). The plural is regular: buoni, buone.

grande may shorten to gran before a consonant (un gran successo, una gran festa) and to grand’ before a vowel (un grand’uomo). Grande in full is always acceptable.

Forms & patterns

Class 1 - four endings (rosso):

Class 2 - two endings (verde):

bello before the noun, matched to the definite article:

buono in the singular, matched to the indefinite article:

Position and meaning:

Examples

Common mistakes

• una casa piccolo -> una casa piccola The adjective must copy the noun’s gender, not stay in the dictionary form.
• una ragazza francesa -> una ragazza francese francese is a class-2 adjective (-e / -i): it has no separate feminine singular. Same for inglese, grande, giovane, difficile, felice.
• le rosse macchine -> le macchine rosse Colours, nationalities and materials always follow the noun.
• Anna e Marco sono contente. -> Anna e Marco sono contenti. A mixed masculine + feminine group takes the masculine plural -i.
• un buono caffè -> un buon caffè Before the noun buono follows the un / uno / una pattern; buono in full only appears where you would say uno.

Tips

• Two classes, two questions. Does the dictionary form end in -o? Then it has four endings. Does it end in -e? Then it has two, and the singular tells you nothing about gender - un problema difficile, una scelta difficile.
• A useful ear-check: the endings -o / -a / -i / -e are the same ones you already saw on nouns in Nouns: gender and number. Le case sono belle rhymes; le case sono bello does not. If the sentence sounds off, it usually is.
• The pre-nominal adjectives are a small, closed list you can memorise (bello, buono, brutto, grande, piccolo, giovane, vecchio, nuovo, bravo, lungo, breve). Everything else you will ever learn goes after the noun. When in doubt, put it after - that is never ungrammatical, at worst slightly emphatic.
• bello before a noun = the definite article with b- in front (il -> bel, gli -> begli). buono before a noun = the indefinite article with buon- in front (un -> buon, uno -> buono). One pattern each, already learned in Definite and indefinite articles.