Something that is subvisual is too small or faint to be seen with the naked eye.
Subvisual things are very tiny or very hard to see.
Examples:
The subvisual particles are too small to see.
She used a microscope to see the subvisual details.
The stars are subvisual during the day.
The subvisual bugs are too small to catch!
The subvisual world is full of tiny surprises.
The subvisual creatures live in a tiny world under the ground.