What does "submicroscopic" mean?

Smaller than microscopic; too small to be seen even with a microscope

Submicroscopic

Common synonyms include: acroscopic, insignificant, microscopically observed, millionths, minuscule, minute.

adj

adj ·Rare ·Advanced level

Adjective

1
Smaller than microscopic; too small to be seen even with a microscope not-comparable

From sub- + microscopic.