Nano

Apparently the iPod nano has good sound.

Source: tatoeba (328351)

The prefix nano stands for one-billionth, and one-billionth of just about any single thing is way too small for the human eye to see.

Source: tatoeba (10935197)

A nanometer, or nano, is one-thousand-millionth of a meter. This is about the size of atoms and molecules. Nanotechnologists work with materials this small.

Source: tatoeba (11131100)

What's surprising is that reducing certain materials from the macro to the nano scale radically changes some of their properties. For example, gold becomes a liquid at room temperatures, aluminum becomes combustible, and silicon turns into a conductor instead of an insulator. So these very small materials behave in ways that are not yet completely understood, and just the fact that they are unimaginably small creates a lot of the controversy. People fear that smaller nanotech particles in the environment might be accidentally absorbed by the human body, that invisible surveillance devices could watch our every move, or that microscopic new weapons would threaten our security in unforeseen ways.

Source: tatoeba (12250679)