Immunity not acquired by vaccination or previous infection; specifically immunity to a particular infection which is inherent in the genetic make-up of an individual, species, family, etc.; also in extended use.
Origin
Late 19th century.
Definition of natural immunity in US English:
natural immunity
noun
Immunity not acquired by vaccination or previous infection; specifically immunity to a particular infection which is inherent in the genetic make-up of an individual, species, family, etc.; also in extended use.