monad (biology) a single-celled microorganism (especially a flagellate protozoan)
intestinal flora harmless microorganisms (as Escherichia coli) that inhabit the intestinal tract and are essential for its normal functioning
virus (virology) ultramicroscopic infectious agent that replicates itself only within cells of living hosts; many are pathogenic; a piece of nucleic acid (DNA or RNA) wrapped in a thin coat of protein
moneran,
moneron organisms that typically reproduce by asexual budding or fission and whose nutritional mode is absorption or photosynthesis or chemosynthesis
bacteria,
bacterium (microbiology) single-celled or noncellular spherical or spiral or rod-shaped organisms lacking chlorophyll that reproduce by fission; important as pathogens and for biochemical properties; taxonomy is difficult; often considered to be plants
microbe,
germ,
bug a minute life form (especially a disease-causing bacterium); the term is not in technical use
pathogen any disease-producing agent (especially a virus or bacterium or other microorganism)
