1) Metric linear unit 2) Micromicron 3) Picometer 4) Unit of length 1) Micromicron 2) Picometer 
The picometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: pm) or picometer (American spelling) is a unit of length in the metric system, equal to one trillionth (i.e., 1/1,000,000,000,000) of a metre, which is the SI base unit of length. It can be written in scientific notation as 1×10−12 m, i...
A distance equal to 10-12 metres. See also: Bicron, Metre.