Nidus

The Latin word for 'nest', nidus is used in medicine to refer to any structure that resembles a nest in appearance or function.

Just as a nest is a repository for the eggs of birds, insects and other animals, a nidus is a breeding place where bacteria, parasites and other agents of a disease lodge and develop.

This is a nidus of infection, a focus of infection.

A nidus is also the nucleus or origin of a nerve.

The nidus avis cerebelli is a deep sulcus (groove) on each side of the inferior vermis (a wormlike structure in the brain), separating it from the adjacent lobes of the cerebral hemispheres.