Definitions for "Femto"
Femto is an SI prefix in the SI system of units denoting 10-15 or one quadrillionth ( e.g. one femtosecond, one femtometer). Adopted in 1964, it comes from the Danish or Norwegian femten, meaning fifteen. Abbreviation
A prefix that stands indicates a factor of 10-15, abbreviated as "f".
Prefix used in the SI system meaning "multiply by 10-15". For example 22 fg means 22× 10-15 g.
(f) = thousand millionmillionth = 0.000000000000001 = 10-15 (see Micros, Millis, Megas and Measurements)
Unit qualifier (symbol = f) representing one thousandth of one millionth of one millionth, or 10-15. For example, 3fS stands for 3 x 10-15 seconds.
Thousand million millionth = 0.000000000000001 = 10-15