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[in-fin-i-tes-uh-muh l] /ˌɪn fɪn ɪˈtɛs ə məl/
indefinitely or exceedingly small; minute:
infinitesimal vessels in the circulatory system.
immeasurably small; less than an assignable quantity:
to an infinitesimal degree.
of, relating to, or involving infinitesimals.
an infinitesimal quantity.
Mathematics. a variable having zero as a limit.
Origin of infinitesimal
1645-55; < New Latin infīnītēsim(us), equivalent to Latin infīnīt(us) infinite + -ēsimus suffix of ordinal numerals + -al1
Related forms
infinitesimality, infinitesimalness, noun
infinitesimally, adverb Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for infinitesimally
Contemporary Examples
Historical Examples
  • He must have been infinitesimally small; but that did not matter.

    Mystic London: Charles Maurice Davies
  • Just think—that sparrow when we last saw it was infinitesimally small.

    The Girl in the Golden Atom Raymond King Cummings
  • Mathematicians, I suppose, could calculate the probabilities, but they must be infinitesimally small.

    Science and Morals and Other Essays Bertram Coghill Alan Windle
  • Their success, of which so much is said in England and America, is "infinitesimally small."

    From Egypt to Japan Henry M. Field
  • This condition will be satisfied if the time of journey down a ray and down all infinitesimally differing paths is the same.

    The Ether of Space Oliver Lodge
  • We are here in presence of geological changes affected neither by shock nor convulsion, nor yet by infinitesimally slow degrees.

    In the Heart of Vosges Matilda Betham-Edwards
  • The inkstand from Italy was large in promise, but poor in fulfillment—the place for ink was infinitesimally small.

    A Few Short Sketches Douglass Sherley
  • One human lifetime is too infinitesimally small to relearn procedures that have taken aeons to develop.

    The Great Gray Plague Raymond F. Jones
  • The trouble is that they are so small, so infinitesimally small, almost.

British Dictionary definitions for infinitesimally


infinitely or immeasurably small
(maths) of, relating to, or involving a small change in the value of a variable that approaches zero as a limit
(maths) an infinitesimal quantity
Derived Forms
infinitesimally, adverb
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
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Word Origin and History for infinitesimally



1710 (1650s as a noun), "infinitely small," from Modern Latin infinitesimus, from Latin infinitus "infinite" (see infinite) + -esimus, as in centesimus "hundredth." Related: Infinitesimally.

Online Etymology Dictionary, © 2010 Douglas Harper
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infinitesimally in Science
Adjective  Capable of having values approaching zero as a limit.

Noun  A function or variable continuously approaching zero as a limit.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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