A burrow is a tunnel or hole that an animal digs underground to live in. Rabbits dig burrows with multiple rooms and escape routes. Prairie dogs create whole underground cities of connected burrows where hundreds of families live together. Foxes, badgers, groundhogs, and many other animals excavate their own burrows for shelter and safety.

The entrance to a burrow might look like a simple hole in the ground, but inside it can be surprisingly complex. A rabbit's burrow, called a warren, might have different chambers for sleeping, storing food, and raising babies. The underground tunnels stay cool in summer and warm in winter, protecting the animals from extreme weather and predators.

As a verb, burrow means to dig such a tunnel, or to nestle or dig into something the way an animal would. You might burrow under your blankets on a cold morning, snuggling deeper to stay warm. A mole burrows through soil looking for earthworms to eat, leaving raised tunnels across lawns.