microbiomenoun [ C ]
uk/ˌmaɪ.krəʊ.ˈbaɪ.əʊm//ˌmaɪ.kroʊ.ˈbaɪ.oʊm/specializedthe microorganisms (= living things too small to be seen) that exist in a particular environment or in the human body:
A Human Microbiome Project is planned to sequence the DNA of the many bacterial species present in humans.