[An organism that can be seen only through a microscope. Microorganisms include bacteria, protozoa, algae, and fungi. Although viruses are not considered living organisms, they are sometimes classified as microorganisms. ( NCI )]
UMLS (NCI) C0445623 Relation/PAR: living system
non-person living subject
Relation/CHD: viroid
virus
attenuated microorganism
Monera
Protista