microorganism
UK: ˌmaɪkrəʊˈɔːɡənɪzəm | US: ˌmaɪkroʊˈɔːrɡənɪzəm
n. a microscopic organism, especially a bacterium, virus, or fungus.
The word "microorganism" combines "micro-" (from Greek mikros, meaning "small") and "organism" (from Greek organon, meaning "tool" or "instrument," later evolving to denote a living structure). The term emerged in the 19th century as advancements in microscopy revealed tiny life forms invisible to the naked eye. The prefix "micro-" logically scales down the concept of an organism, emphasizing its minuscule size.
Scientists study microorganisms to understand their role in ecosystems.
Some microorganisms are beneficial, aiding digestion in humans.
Water treatment plants filter out harmful microorganisms.
Pasteurization kills pathogenic microorganisms in milk.
The human body hosts trillions of microorganisms, collectively called the microbiome.