Nano-

nano, n -

1. The SI definition, a prefix used to form decimal submultiples of the SI unit "meter", designating a factor of 10-9 denoted by the symbol "n".
2. Pertaining to things on a scale of approximately 1 to 100 nanometers (nm).
3. A prefix referring to an activity, material, process or device that pertains to a field of knowledge defined by nanotechnology and nanoscience.

Source:
ASTM International. E 2456–06. Terminology for Nanotechnology