Domestic warrens are artificial, enclosed establishments 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.
The cunicularia of the monasteries may have more closely resembled hutches or pens, than the open enclosures with specialized structures which the domestic warren eventually became.
These were "pillow-like", oblong mounds with flat tops, frequently described as being "cigar-shaped", and sometimes arranged like the letter ⟨E⟩ or into more extensive, interconnected rows.
By 1649, the term was applied to inferior, crowded human accommodations and meant "cluster of densely populated living spaces" (OED).