submicroscopic

sub·mi·cro·scop·ic

adj \ˌsəb-ˌmī-krə-ˈskäp-ik\

Definition of SUBMICROSCOPIC

: too small to be seen in an ordinary light microscope <submicroscopic particles> <submicroscopic organization of a bacterium>—compare macroscopic, microscopic 2, ultramicroscopic 1

—sub·mi·cro·scop·i·cal·ly \-i-k(ə-)lē\ adverb