nano- Placing nano- before a word indicates that the thing referred to is submicroscopically small; technically, it refers to a factor of a thousandth of a million (10⁻⁹). A nanosecond is one thousand millionth of a second, while nanotechnology deals with the manipulation of individual atoms and molecules.

Nano- comes from the Greek word nanos, meaning ‘dwarf’. It was adopted in English as early as 1947, although nano- words only entered most people’s consciousness in the 1990s, when technology using very small components had been developed.