Source : Webster's Revised Unabridged Dictionary (1913)

Microcosm \Mi"cro*cosm\, n. [F. microcosme, L. microcosmus, fr.
   Gr. mikro`s small + ko`smos the world.]
   A little world; a miniature universe. Hence (so called by
   Paracelsus), a man, as a supposed epitome of the exterior
   universe or great world. Opposed to {macrocosm}. --Shak.

Source : WordNet®

microcosm
     n : a miniature model of something