ˈmīkrəˌsōm noun
( -s )
Etymology: German mikrosom, from mikr- micr- + -som -some
1. : any of various minute structures of the cell especially as observed at the limit of resolution of the light microscope
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