animalcule

from WordNet (r) 3.0 (2006)

animalcule
    n 1: microscopic organism such as an amoeba or paramecium [syn:
         {animalcule}, {animalculum}]

from The Collaborative International Dictionary of English v.0.48

Animalcule \An`i*mal"cule\, n. [As if fr. a L. animalculum, dim.
   of animal.]
   1. A small animal, as a fly, spider, etc. [Obs.] --Ray.
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   2. (Zool.) An animal, invisible, or nearly so, to the naked
      eye. See {Infusoria}.
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   Note: Many of the so-called animalcules have been shown to be
         plants, having locomotive powers something like those
         of animals. Among these are {Volvox}, the
         {Desmidiac[ae]}, and the siliceous {Diatomace[ae]}.
         [1913 Webster]

   {Spermatic animalcules}. See {Spermatozoa}.
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