microorganism
Concise Oxford English Dictionary © 2008 Oxford University Press:
microorganism
▶noun a microscopic organism, especially a bacterium, virus, or fungus.
'microorganism' also found in these Oxford entries:
avirulent
- bug
- extremophile
- fix
- germ
- isolate
- methanogen
- microbe
- nanobacterium
- pathogen
- saprophyte
- serotype
- thermophile
- toxin
- toxoid

