1. (尤指通常由人饲养的动物)野生的，未驯服的
Feral animals are wild animals that are not owned or controlled by anyone, especially ones that belong to species which are normally owned and kept by people.
2. 狂野的;狂暴的;桀骜不驯的
If you describe something or someone as feral, you mean that they seem wild, fierce, and uncontrolled.