nano- is a prefix (symbol n) in the SI system of units denoting a factor of 10−9. It is often used in prefixing time and length units encountered in electronics and computer systems, like 30 nanoseconds (symbol ns) and 100 nanometres (nm). It was confirmed in 1960 and comes from the Greek νᾶνος, meaning dwarf. In the United States, the use of the nano- prefix for the farad unit of electrical capacitance is uncommon; capacitors of that size are more often expressed in terms of a small fraction of a microfarad or a large number of picofarads.
When used as a prefix for something other than a unit of measure, as in "nanoscience", nano- means relating to nanotechnology, or on a scale of nanometers.