Ask a chemist and he will talk about particles on the nanometer scale (0,000000001m), a pharmacist might emphasize how these nanoparticles can permeate through your skin, the physicist, meanwhile, thinks of semiconductor-structures as you have them in your computer-chips.
So, what the heck is Nano?
The European Commission is asking you (and me and your neighbour plus some friends - literally everybody) to find a definition of the term "nanomaterial" that the European Commission may use as an overarching, broadly applicable reference term for any EU communication addressing nanomaterials.
You may discuss them with us here, or go directly to the EU website.
You might help prevent "Nano" from bearing any bias like "Atom" or "Gene".