1. A blood relative; a person connected by birth rather than by marriage or adoption
She wanted to find her natural relatives after being adopted as a child.
Ela queria encontrar seus parentes biológicos depois de ter sido adotada na infância.
2. In biology, an organism that is closely related through evolutionary descent
The chimpanzee is considered one of humans' closest natural relatives.
O chimpanzé é considerado um dos parentes naturais mais próximos do ser humano.