[ 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.

Nearby words

  1. infinite integral,
  2. infinite product,
  3. infinite regress,
  4. infinite series,
  5. infinitely,
  6. infinitesimal calculus,
  7. infinitival,
  8. infinitive,
  9. infinitive clause,
  10. infinitive marker

Origin of infinitesimal

1645–55; < New Latin infīnītēsim(us), equivalent to Latin infīnīt(us) infinite + -ēsimus suffix of ordinal numerals + -al1

Related formsin·fin·i·tes·i·mal·i·ty, in·fin·i·tes·i·mal·ness, nounin·fin·i·tes·i·mal·ly, adverb Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for infinitesimally

British Dictionary definitions for infinitesimally


/ (ˌɪnfɪnɪˈtɛsɪməl) /


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 Formsinfinitesimally, 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

Science definitions for infinitesimally


[ ĭn′fĭn-ĭ-tĕsə-məl ]


Capable of having values approaching zero as a limit.


A function or variable continuously approaching zero as a limit.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.