<optics> Particles which, although visible in the ultramicroscope, are too small to be resolved by visible light. This places their size between 0.2 Lm and 0.005 Lm. ... (05 Aug 1998) ... 
(sub″mi-kro-skop´ik) too small to be visible with the microscope.
Type: Term Pronunciation: sŭb′mī-krō-skop′ik Definitions: 1. Too minute to be visible with a light microscope. Synonyms: amicroscopic, ultramicroscopic
too small to be seen through a microscope.