1. genetics a condition that prevents or limits breeding among populations, e.g., phenological differences in flowering time, chromosome difference, or distance —see allopatric, incompatibility, phenology, sterility 2. pathology the process of placing an organism in pure culture by separating it from host tissues or surfaces, contaminants, infestations, and secondary pathogens —note isolation is usually done for purposes of identification and by means of cultureThis definition last updated 10/28/2008