hypervariable regions

hy·per·var·i·a·ble re·gions

(hī-per'var-ī-a-ble), the regions of the immunoglobulin molecule that contain most of the residues involved in the antibody binding site. Hypervariability at the site of antigen building ensures the broadest immunologic repertoire.

hypervariable regions

The parts within the antibody and T cell receptor variable regions which show the greatest variability.