Possessive pronouns indicate to whom something belongs. They agree with the person who possesses, and in Portuguese they can also agree with the gender and number of the possessed object. The sentence needs to clearly show who the possessor is to avoid ambiguities. The context can determine whether "seu" refers to the speaker, the addressee, or someone else.

The basic forms of possessive pronouns are: meu, minha, teu, tua, seu, sua, nosso, nossa, vosso, vossa. They pair with the noun they are determining. The choice between masculine and feminine forms depends on the noun, not the possessor. The plural of possessives appears when the noun is plural.

The possessive agrees with the noun in gender and number. Use "my" and "my" for singular, "my" and "my" for plural. The same logic applies to "teu/teus", "tua/tuas", "seu/seus" and "sua/suas". "Nosso" and "nossa" also form "nossos" and "nossas".

The choice among "my", "your", "his/her/your", "our" and "your" (plural) depends on who is speaking and to whom they are addressing. "Meu" and "minha" belong to the I, "teu" and "tua" belong to you (singular), "seu" and "sua" belong to he, she, you and, often, to names or titles. "Nosso" and "nossa" belong to us, and "vosso" and "vossa" belong to you (plural), though "vosso" is rare in everyday Brazilian speech.

"Seu" can be ambiguous because it may refer to "you" or to "he/she". In Portuguese, especially in Brazil, the sentence can become confusing without context. To avoid ambiguity, it is common to repeat the possessor's name or use alternative structures. Clarity is more important than merely following the form.

The possessive usually appears before the noun: "my book", "our house". It can appear after the noun in more formal or poetic language: "a friend mine". With words like "one" or "none", the possessive tends to come after: "a friend mine". The order can change the tone or emphasis, but it does not change ownership.

The plural of possessives is formed by adding "s" to forms that already end in a vowel: "meus", "minhas", "teus", "tuas", "seus", "suas", "nossos", "nossas". Use the plural when there is more than one possessed object. The possessor can be singular or plural, but the possessive accompanies the possessed noun. "Nossos" and "nossas" indicate possession by us with a plural noun.

In Brazil, "seu" is the possessive most used with "você" because "você" is common in speech. "Teu" appears more in regions where "tu" is used frequently, such as in the South and parts of the Northeast. "Vosso" is rare in Brazilian speech and appears more in formal contexts or old texts. In Portugal, "tu/teu" and "vós/vosso" can be more frequent depending on the situation.

In Portuguese, it is common to use the definite article with body parts instead of the possessive, especially when the possessor is already clear. The possessive appears when there is contrast, emphasis, or risk of ambiguity. With verbs like "wash" and "hurt", the article often sounds more natural. The choice depends on the context and the clarity of the sentence.

The construction "de + name" or "de + pronoun" expresses possession without using the possessive and increases clarity. It is widely used to avoid ambiguity with "seu". It is also common to indicate possession with titles, positions, or proper names. The structure works well in both formal and informal language.