Microscopic (adjective)

So small as to be visible only with a microscope.

Origin:

From micro- + -scopic.

Examples:

1. The bacteria are too small to be seen with the naked eye, they are microscopic.
2. The scientist observed the microscopic structure of the cell.
3. The microscopic organisms play an important role in the ecosystem.
4. The microscopic fibers in the tissue are responsible for its strength.
5. The microscopic details of the painting were stunning.