DEFINITE AND INDEFINITE ARTICLE

Gender

Nouns have two genders, masculine and feminine. Some nouns (professions, persons, animals) have both masculine and feminine form (E.g. a amiga and o amigo, a irmã (sister), o irmão (brother)).

Indefinite

masculinefeminine

singularum (carro)uma (casa)

plural(alg)uns (carros)(alg)umas (casas)

In theory indefinite plural form has article, but in practise the plural is just the noun alone. (Alg)uns or (alg)umas can be used to emphasize the meaning "some". So this table in practise would look like this:

masculinefeminine

singularum (carro)uma (casa)

plural(carros)(casas)

Indefinite article merges with with de and em prepositions.

Definite

masculinefeminine

singularo (carro)a (casa)

pluralos (carros)as (casas)

Definite article merges with a, de, em and por prepositions.