What's the "een" in Halloween?
late 14c., "exempt from service or obligation," 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" (see in- (1)) + munis "performing services" (cf. municipal), from PIE *moi-n-es-, suffixed form of root *mei- "to change" (see mutable). Medical sense "protection from disease" is 1879, from French or German.
immunity im·mu·ni·ty (ĭ-myōō'nĭ-tē)
The quality or condition of being immune.
Inherited, acquired, or induced resistance to infection by a specific pathogen.
The protection of the body from a disease caused by an infectious agent, such as a bacterium or virus. Immunity may be natural (that is, inherited) or acquired. See also acquired immunity.
The ability of the body to resist or fight off infection and disease.