Immune means protected from an illness so that it cannot take hold. Immune to measles, immune system, immune response.
Immunity comes from having had the disease or from a vaccine, and the immune system is the whole apparatus that provides it. Immunocompromised means that system is weakened. Figuratively, immune to means unaffected by: immune to criticism, immune to flattery. In law, immunity is protection from prosecution — diplomatic immunity, immunity from prosecution. Note immunise and immunology.
1adjectiveimmuneProtected from an illness so it cannot take hold.
“Once you've had chickenpox, you're usually immune to it for life.”
2adjectiveunaffectedUnaffected by something.
“He is entirely immune to flattery, which makes him difficult.”
immune is a state of protection.
Latin immunis meant exempt from public service or tax — in-, not, plus munus, a duty. The medical sense is a nineteenth-century borrowing of the legal one: an immune body is exempt from the disease.
Latin
immūnis
Middle French
immun
English, today
immune
Built from
From Middle English -, from Middle French immun, from Latin immūnis. From Middle English -, from Middle French immun, from Latin immūnis (“exempt from public service”), from in- (“not”) + mūnus (“service”).
Etymology from Wiktionary, CC BY-SA