/iˈmyo͞onitē/
Noun, pl. immunities
1.(Medical) Resistance of an organism to infection or disease (wikipedia.org); fully protective resistance against infection.(wiktionary.org)
2. Inherited, acquired, or induced resistance to infection by a specific pathogen. (medical-dictionary.thefreedictionary.com)
3. The ability of an organism to resist disease, either through the activities of specialized blood cells or antibodies produced by them in response to natural exposure or inoculation (active immunity) or by the injection of antiserum or the transfer of antibodies from a mother to her baby via the placenta or breast milk (passive immunity). (thefreedictionary.com)
4. The condition of being immune, the protection against infectious disease conferred either by the immune response generated by immunisation or previous infection or by other nonimmunologic factors. (biology-online.org)
Word origin: From Old French immunité and directly from Latin immunitatem (nominative immunitas) “exemption from performing public service or charge,” from immunis “exempt, free,” from assimilated form of in- “not, opposite of” + munis “performing services”