A feral animal or plant (from Latin: 'fera', 'a wild beast') is one that lives in the wild but is descended from domesticated individuals. As with an introduced species, the introduction of feral animals or plants to non-native regions may disrupt ecosystems and has, in some cases, contributed to extinction of indigenous species.

A feral animal is one that has escaped from a domestic or captive status and is living more or less as a wild animal, or one that is descended from such animals. Other definitions include animals that have changed from being domesticated to being wild, natural, or untamed. Some common examples of animals with feral populations are horses, dogs, goats, cats, rabbits, camels, and pigs. Zoologists generally exclude from the feral category animals that were genuinely wild before they escaped from captivity: neither lions escaped from a zoo nor the white-tailed eagles re-introduced to the UK are regarded as feral.

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