1.Definition: (usually followed by `to') not affected by a given influence

"Immune to persuasion"

2.Definition: relating to or conferring immunity (to disease or infection)

Related Adjective(s):resistant

3.Definition: relating to the condition of immunity

"The immune system"

4.Definition: secure against

"Immune from taxation as long as he resided in Bermuda", "Immune from criminal prosecution"