A warren is a network of wild rodent or lagomorph, typically rabbit burrows. Domestic warrens are artificial, enclosed establishment of animal husbandry dedicated to the raising of rabbits for meat and fur. The term evolved from the medieval Anglo-Norman concept of free warren, which had been, essentially, the equivalent of a hunting license for a given woodland. Ultimately, the term "warren" was generalized to include wild burrows. The use is further extended to any system of burrows, e.g., "prairie dog warren".

Source: Wikipedia