From Latin 'immūnis' (exempt from duty) — a legal tax-exemption term repurposed in the 1880s for the body's disease resistance.
Resistant to a particular infection or toxin owing to the presence of specific antibodies or sensitized white blood cells; also, protected or exempt from an obligation or penalty.
From Latin 'immūnis' (exempt from public service, free from a charge or duty), formed from 'in-' (not) + 'mūnis' (performing services, under obligation), related to 'mūnus' (a duty, an office, a gift). The original meaning was purely legal and civic: an 'immunis' person was someone exempted from taxes or public duties. The biological meaning — resistance to disease — only emerged in the late