Source : Webster's Revised Unabridged Dictionary (1913)

Nidus \Ni"dus\, n.; pl. {nidi}. [L. See {Nidi}, {Nest}.]
   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.

Source : WordNet®

nidus
     n 1: a central point or locus of an infection in an organism;
          "the focus of infection" [syn: {focus}, {focal point}]
     2: a nest in which spiders or insects deposit their eggs
     [also: {nidi} (pl)]

nidi
     See {nidus}