Inate immunity

resistance manifested by a species (or by races, families, and individuals in a species) that has not been immunized (sensitized, allergized) by previous infection or vaccination

Definition
Inate immunity in humans results from body mechanisms that are poorly understood, but are different from those responsible for the altered reactivity associated with the specific nature of acquired immunity; in general, innate immunity is nonspecific and is not stimulated by specific antigens Syn natural immunity