What is a nest: a repository for the eggs of birds, insects, etc.; a breeding place; esp., the place or substance where parasites or the germs of a disease effect lodgment or are developed called?

nidus — A nest: a repository for the eggs of birds, insects, etc.; a breeding place; esp., the place or substance where parasites or the germs of a disease effect lodgment or are developed. (Webster's 1913.)