femto-

femto-

pref.

One quadrillionth (10^-15): femtovolt.

---

[From Danish and Norwegian femten, fifteen, from Old Norse fimmtān; see penk^we in Indo-European roots.]

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

femto-

prefix

(Units) denoting 10^–15: femtometer. Symbol: f

[from Danish or Norwegian femten fifteen]

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

femto-

a combining form used in the names of units of measure that are one quadrillionth (10⁻¹⁵) the size of the unit denoted by the base word: femtogram.

[< Dan, Norwegian femt(en) fifteen + -o-]

Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.

femto-

A prefix meaning 1 quadrillionth (10-15).

Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited