Glossary of Terms

Common terms that you may encounter on the site.


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A (9) | B (2) | C (2) | D (2) | E (6) | G (1) | H (2) | I (8) | K (1) | L (1) | M (2) | P (5) | R (1) | S (5) | T (4) | U (1) | V (6)

  • IgG

    Antibody molecules secreted by B cells. IgG is the most abundant antibody found in gamma globulin.

  • Immune system

    The collection of organs, cells, and molecules that make up an organism’s response to a disease threat or foreign substance.

  • Immunity

    The state of an individual’s existing resistance to a pathogen, whether conferred by a previous infection (“natural immunity”), or via vaccination.

  • Immunization

    A procedure for creating resistance to a pathogen. Such procedures include vaccination and treatment with antibodies.

  • Immunogen

    A substance able to provoke an immune response. (“Immunogenicity” refers to an immunogen’s ability to provoke such a response under particular circumstances.)

  • Inactivated vaccine

    A type of vaccine in which the vaccine pathogen (a viral or bacterial) is killed or otherwise altered so that it cannot cause infection, but can still provoke an immune response. Immunity generated in response to inactivated vaccines typically does not last as long as immunity from live, attenuated vaccines.

  • Infectious disease

    An illness caused by a pathogen that invades an organism.

  • Inoculation

    The introduction of material into a person in order to provoke immunity to a disease. “Inoculate” is often used to refer to the historical practice of variolation. (See Variolation.)