1. A journey or voyage that is distinctive, one-of-a-kind, and notably different from others in its purpose, route, or execution
The Arctic exploration team embarked on a unique expedition to study climate change effects.
A equipe de exploração do Ártico iniciou uma expedição única para estudar os efeitos das mudanças climáticas.
2. An unusual or special exploratory mission characterized by novel methods or objectives
This unique expedition combines scientific research with documentary filmmaking.
Esta expedição única combina pesquisa científica com produção de documentário.