■ adjective
1》 resistant to a particular infection owing to the presence of specific antibodies or sensitized white blood cells.
↘ Biology relating to such resistance: the ~ system.
2》 exempt from an obligation or penalty.
3》 (often ~ to ) not affected by something.
Origin
ME: from L. immunis 'exempt from public service or charge', from in- 'not' + munis 'ready for service'.