(n.) Any microscopic form of life; -- particularly applied to bacteria and similar organisms, esp. such are supposed to cause infectious diseases.

Euglena adenovirus aerobe aerobic bacteria aerobic organism amoeba anaerobe anaerobic bacteria anaerobic organism animalcule autotrophic organism bacillus bacteria bacterium being bug coccus colon bacillus creature crumb diatom disease-producing microorganism dot drop droplet dyad echovirus enterovirus filterable virus flagellate fleck flyspeck fungus genetic individual germ gnat grain gram-negative bacteria gram-positive bacteria heterotrophic organism individual iota jot living being living thing microbe microspore microzoa midge minim minutia minutiae mite mold monad morphological individual mote nematode nonfilterable virus ont organic being organism organization paramecium particle pathogen physiological individual picornavirus pinhead pinpoint point protozoa protozoon reovirus rhinovirus rickettsia salmonella saprophyte scrap snip snippet speck spirillum spirochete spore sporozoon staphylococcus streptococcus tetrad tittle triad trypanosome vanishing point vibrio virus volvox vorticellum zooid zoon zoospore