an·i·mal·cule 
(ăn′ə-mălkyl) also an·i·mal·cu·lum (-kyə-ləm)
(ăn′ə-mălkyl) also an·i·mal·cu·lum (-kyə-ləm)n. pl. an·i·mal·cules also an·i·mal·cu·la (-kyə-lə)
1. A microscopic or minute organism, such as an amoeba or paramecium, usually considered to be an animal.
2. Archaic A tiny animal, such as a mosquito.
[New Latin animalculum, diminutive of Latin animal, animal; see ANIMAL.]