Too small to be resolved by an optical microscope.(adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "submicroscopic" in a sentence
"The true life takes place when we're alone, thinking, feeling, lost in memory, dreamingly selfaware, the submicroscopic moments."
"The key to the Feynman Drive is a submicroscopic sample of the hypothetical element Feynmanium, named after my real-life mentor and co-author from my Caltech days."
"Against violent and cunning opposition, the three of them unearth a scheme to capture the submicroscopic black hole that caused the Tunguska Event and use its awesome power to transform the world -- or end it altogether."