A nanometer (common symbol nm) is a unit of length which is equal to one billionth of a meter (i.e., one millionth of a millimeter). 1 nm = 1x10-9 m. The prefix "nano" comes from the Greek language word: νάνος (nanos), which means dwarf.
A nanometer is a standard unit of length used when referring to very small length scales, such as that used in nanotechnology. Another common unit of length used for very small length scales, which is also internationally recognized, is the Ångström unit with the symbol Å. One nm is equal to 10 Å. Ångström unit is not a recognized SI length unit.
Typically, the term nanoscale is used to refer to objects with dimensions on the order 1–100 nm. The term is often heard in relation to nanotechnology.