cross-link

n. (Chem., Biochem.) a covalent bond that links two chains of atoms, or two sections of one chain, in a polymeric molecule; the cross-link is created by a third bond in a monomer unit in addition to the two bonds forming the polymeric chain; -- a cross-link may be internal to a single chain, rather than between two otherwise unlinked chains; as, ultraviolet irradiation creates cross-links between the two chains of a DNA double helix; many enzymes have cross-links formed by disulfide bonds; polystyrene resins have their porosity controlled by the proportion of cross-links. Called also cross-linkage.
Syn. -- cross-linkage. [ WordNet 1.5 ]