microorganism Meaning, Definition & Usage

  1. noun any organism of microscopic size
    micro-organism.

WordNet

Mi`cro*ör"gan*ism noun (Also<
  • Microorganism
  • Microörganism
)
Etymology
Micro- + organism.
Definitions
  1. (Biol.) Any microscopic form of life; -- particularly applied to bacteria and similar organisms, esp. such are supposed to cause infectious diseases.

Webster 1913