nidus ni·dus (nī'dəs)
n. pl. ni·dus·es or ni·di (-dī)
A central point or focus of bacterial growth in a living organism.
A nest, especially one for the eggs of insects, spiders, pathogenic organisms, or small animals.
A cavity where spores develop.
A point or place at which something originates, accumulates, or develops, as the center around which calculi form.