microscopic

Short definition from Wiktionary

Adjective

1. 1
   Of, or relating to microscopes or microscopy; microscopal
2. 2
   So small that it can only be seen with the aid of a microscope.
3. 3
   Very small; minute
4. 4
   Carried out with great attention to detail.
5. 5
   Able to see extremely minute objects.