How do we decide when to use dele, dela, deles, delas vs. seu, sua, seus, suas?
Possessives formed with de are less ambiguous: they agree strictly with the subject, not with the object. In contrast, seu and its derivatives agree with the object, so we are not able to differentiate between the several possible 3rd person subjects without extra context.
Dele, dela, deles, delas
- dele his – When the subject is ele (him).
- dela her – When the subject is ela (her).
- deles their – When the subject is eles (them, a group with at least one male).
- delas their – When the subject is elas (them, an all-female group).
Seu, sua, seus, suas
These are also used for the same 3rd person subjects, but the specific form used must match the gender and number of the object/noun being modified, instead of the subject.
- seu (masc. object) or sua (fem. object) – For a single object, regardless of which subject
- seus (masc. objects) or suas (fem. objects) – For multiple objects, regardless of which subject
Disambiguation with Dele(s) and Dela(s)
Let’s say we had uma caneta a pen (fem. noun) and um lápis a pencil (masc. noun) and want to talk about who each belongs to. Notice that the examples below using seu and sua are all the same, despite very different meanings, which are revealed with the use of dele(s) and dela(s).
Single male subject (ele):
Single female subject (ela):
Collective male subject (eles):
Collective female subject (elas):
What About the Pronoun Você?
Você is a second-person singular pronoun, but used with a third-person framework, which is why it also uses seu and its derivatives. Unlike the actual third-person pronouns (ele and ela), você can’t be combined with de in European Portuguese.
In Portugal, people tend to reserve seu(s) and sua(s) for instances in which the pronoun você is implied, while favouring dele(s) and dela(s) for the other third-person subjects:
O seu carro e a sua casa. Your formal car and your formal house.
O carro e a casa dele. His car and house.
O carro e a casa dela. Her car and house.
O carro e a casa deles. Their masc. car and house.
O carro e a casa delas. Their fem. car and house.