| the binding of complement to immune complexes or to certain foreign surfaces, as those of invading microorganisms. |

| complement fixation n. The binding of active serum complement to an antigen-antibody pair. It is the basis for various diagnostic tests to detect the presence of a specific antigen or antibody. |
complement fixation n.
The binding of active complement to a specific antigen-antibody pair used in diagnostic tests, such as the Wasserman test, to detect the presence of a specific antigen or antibody.