Noun

1. A structure in which animals lay eggs or give birth to their young
2. A kind of gun emplacement
3. A cosy or secluded retreat
4. A gang of people (criminals or spies or terrorists) assembled in one locality
5. Furniture pieces made to fit close together

Verb

1. Inhabit a nest, usually after building
2. Fit together or fit inside
3. Move or arrange oneself in a comfortable and cozy position
4. Gather nests