n 1  :  any of various minute cellular structures (as a ribosome)  2  :  a particle in a particulate fraction that is obtained by heavy centrifugation of broken cells and consists of various amounts of ribosomes, fragmented endoplasmic reticulum, and mitochondrial cristae mi*cro*som*al adj 
 
 
 
Similar sounding terms:  mac·ro·so·mia  mi·cro·so·mia 
 
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