il

Il is the masculine singular definite article in Italian. It accompanies nouns to indicate that the noun is specific or already known to the listener, and it agrees with the gender and number of the noun. The standard forms are il, lo, l', i, and gli, while the feminine forms are la and le. The form l' is a before-vowel contraction used for both masculine and feminine singular nouns.

The form il is used before masculine singular nouns that begin with a consonant, as in il libro (the book) or il ragazzo (the boy). Lo is used before certain clusters that can be phonetically difficult, notably nouns beginning with s plus a consonant, z, ps, gn, x, or y, for example lo studente, lo zaino. Before nouns that begin with a vowel, the article contracts to l', as in l'amico or l'acqua. The feminine nouns follow the same pattern for singulars: la before consonants (la casa), and l' before vowels (l'idea).

For plural nouns, the masculine forms are i and gli. I is used before most masculine plural nouns that begin with consonants, as in i libri. Gli is used before masculine plural nouns that begin with a vowel or certain clusters (s+consonant, z, gn, ps, x, y), as in gli amici, gli zaini. The feminine plural is le, as in le case, le amiche.

The Italian definite article derives from Latin ille/illa illud and is a fundamental element of Italian grammar, marking definiteness and agreeing with the noun it accompanies.