microorganism

noun

1. An organism that is too small to be seen by the unaided eye; especially, a single-celled organism, such as a bacterium.

   “The cud is then reswallowed by the ruminant and further digested by specialized microorganisms that live in the rumen.”

   “Bacillus anthracis: from the first up to the sixth day, this microorganism was isolatable, or in other words still alive.”

   “The differences in biofilm penetration patterns of both tested photosensitisers and the light source could have played an important role for the survival of microorganisms after the application of aPDT. In a recent own study, we showed that the deepest layers of the oral biofilm were not affected by the aPDT [4 ].”