immune
adj.
mid-15c., "free; exempt," back-formation from immunity. Latin immunis meant "exempt from public service, free from taxes." Specific modern medical sense of "exempt from a disease" (typically because of inoculation) is from 1881. Immune system attested by 1917.
〔李〕[im-(in-);mun;-e] a.免疫的； 免除的 n.免疫力 ←mun (L munus,munia)=service or official duty 服务，职责