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.
Origin of femto-
< Danish, Norwegian femt(en) fifteen + -o-
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British Dictionary definitions for femto-
denoting 10 –15femtometer Symbol: f
Word Origin for femto-
from Danish or Norwegian femten fifteen
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Medicine definitions for femto-
One quadrillionth (10-15):femtovolt.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.