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  1. Microorganism - Wikipedia

    A microorganism, or microbe, [a] is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from …

  2. Microbiology | Definition, History, & Microorganisms | Britannica

    4 days ago · Microorganisms are of incalculable value to Earth’s ecology, disintegrating animal and plant remains and converting them to simpler substances that can be recycled in other organisms. …

  3. MICROORGANISM Definition & Meaning - Merriam-Webster

    The meaning of MICROORGANISM is an organism (such as a bacterium or protozoan) of microscopic or ultramicroscopic size.

  4. Microorganism – Definition, Types, Importance, Examples

    Mar 28, 2024 · A microorganism, or microbe, is a tiny living organism that is invisible to the naked eye and can exist as single-celled entities or colonies of cells.

  5. Microorganisms - GeeksforGeeks

    Nov 19, 2025 · Microorganisms are microscopic life forms that are found everywhere. They can be unicellular or multicellular and can be harmful or beneficial. They play diverse roles in nutrient …

  6. Microorganism - New World Encyclopedia

    A microorganism, or microbe, is an organism (form of life) that is microscopic (too small to be seen by the unaided human eye). Microorganisms can be bacteria, fungi, archaea, or protists, but not viruses …

  7. The Five Major Types of Microorganisms

    Aug 4, 2025 · Microorganisms are essential to life. They ferment our food, enrich our soil, fix nitrogen, decompose the dead, and help regulate the climate. Some cause disease and devastation, but many …

  8. Microorganism - ScienceDaily

    Feb 21, 2023 · A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye).

  9. Microorganism - Definition, Types, Examples & Quiz | Biology Dictionary

    Apr 29, 2017 · A microorganism is a living thing that is too small to be seen with the naked eye. Examples of microorganisms include bacteria, archaea, algae, protozoa, and microscopic animals …

  10. 1.1A: Defining Microbes - Biology LibreTexts

    A microbe, or microorganism, is a microscopic organism that comprises either a single cell (unicellular); cell clusters; or multicellular, relatively complex organisms.