1. Either of the two rounded portions of the human posterior; the gluteal region
He fell and landed on his buttock.
Ele caiu e pousou na nádega.
2. The posterior part of the body of a person or animal, especially when viewed as a source of humor or embarrassment
The baby's buttocks were covered in a diaper rash.
As nádegas do bebê estavam cobertas com assadura.