homunculus

from WordNet (r) 3.0 (2006)

homunculus
    n 1: a person who is very small but who is not otherwise
         deformed or abnormal [syn: {manikin}, {mannikin},
         {homunculus}]
    2: a tiny fully formed individual that (according to the
       discredited theory of preformation) is supposed to be present
       in the sperm cell

from The Collaborative International Dictionary of English v.0.48

Homunculus \Ho*mun"cu*lus\, n.; pl. {Homunculi}. [L., dim. of
   homo man.]
   A little man; a dwarf; a manikin. --Sterne.
   [1913 Webster]