Antiantibody is a term used in immunology to describe a substance that neutralizes the function of an antibody. Synonyms for antiantibody include antireceptor, antinuclear, antiviral, and antitoxin. Antireceptor refers to a substance that binds to and inhibits the function of cell surface receptors. Antinuclear describes a substance that inhibits the function of nuclear enzymes, while antiviral is a substance that fights against viruses. Antitoxin refers to a substance that neutralizes the effect of toxins produced by microorganisms. These terms are all used interchangeably to describe substances that counteract the effects of antibodies and are important in the immune response against pathogens.