A nest is a structure that birds and some other animals build as a safe place to lay eggs and raise their young. Birds gather twigs, grass, mud, and other materials to weave together a cozy shelter, usually hidden in trees, bushes, or under building eaves. Different birds build remarkably different nests: robins make cup-shaped nests of mud and grass, eagles construct massive stick platforms that can weigh hundreds of pounds, and hummingbirds create tiny nests no bigger than a walnut using spider silk and moss.

Many other animals nest too. Squirrels build leafy nests called dreys high in trees. Sea turtles dig nests in beach sand. Wasps and hornets construct paper nests from chewed wood pulp. Alligators pile up vegetation into mound nests that use the heat from rotting plants to warm their eggs.

As a verb, nest means to settle into a snug, protected place. The word also describes cozy spaces where people feel safe and comfortable. Your bedroom might feel like your own little nest. When someone talks about their nest egg, they mean money they've saved and protected for the future. Parents whose children have grown up and moved away sometimes say they have an empty nest.