1. A formal written record issued by a government, organization, or authority that serves as proof or evidence of something
You need an official document to prove your identity at the airport.
Você precisa de um documento oficial para comprovar sua identidade no aeroporto.
2. A legally binding or authenticated paper that certifies facts, rights, or transactions
The birth certificate is an official document required for school enrollment.
A certidão de nascimento é um documento oficial necessário para a matrícula escolar.