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femto-

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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.

QUIZZES

QUIZ YOURSELF ON “THEIR,” “THERE,” AND “THEY’RE”

Are you aware how often people swap around “their,” “there,” and “they’re”? Prove you have more than a fair grasp over these commonly confused words.
Question 1 of 7
Which one of these commonly confused words can act as an adverb or a pronoun?

Origin of femto-

<Danish, Norwegian femt(en) fifteen + -o-
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

British Dictionary definitions for femto-

femto-

prefix

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

Medical definitions for femto-

femto-

pref.

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.
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