femto-

1. a combining form used in the names of units of measurement which are 10− 15 (one quadrillionth) smaller than the unit denoted by the base word.

femto-

prefix

1. denoting 10 ^–15 f

   femtometer

Word History and Origins

Origin of femto-¹

< Danish, Norwegian femt ( en ) fifteen + -o-

Word History and Origins

Origin of femto-¹

from Danish or Norwegian femten fifteen