Feral (adjective)

1. Wild, especially of an animal that has returned to the wild after domestication.
2. Having returned to an untamed state from domestication.
3. Existing in a natural state and not domesticated or cultivated.

Origin:

Late middle english: from latin feralis, from ferus wild.

Examples:

1. Feral cats are often found in urban areas.
2. He saw a feral dog running through the streets.
3. The island was home to a population of feral pigs.
4. Feral children are those who have grown up without human contact.
5. Feral horses can be found in the western United States.