infinitesimal
Americanadjective
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exceedingly small; minute.
Capillaries, the infinitesimal vessels in our circulatory system, are small enough that red blood cells must flow through them single-file.
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Mathematics.
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immeasurably small; less than an assignable quantity.
An infinitesimal number is never zero, but it comes pretty close.
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of, relating to, or involving variables having zero as a limit.
infinitesimal calculus.
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noun
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an infinitesimal quantity.
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Mathematics. a variable having zero as a limit.
adjective
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infinitely or immeasurably small
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maths of, relating to, or involving a small change in the value of a variable that approaches zero as a limit
noun
Other Word Forms
Etymology
Origin of infinitesimal
First recorded in 1645–55; from New Latin infīnītēsim(us), equivalent to Latin infīnīt(us) infinite + -ēsimus suffix of ordinal numerals + -al 1
Explanation
When it's incalculably small, when teensy seems large compared to it, then it is infinitesimal. "The equipment was so sensitive that even the infinitesimal dust molecules that swept in with the open door altered the readings." Infinitesimal is such an extreme description of a microscopic something that the word is used as an exaggeration more often than to describe something actually quite small. "The chances of Roxy going out on a date with Norbert were infinitesimal. She barely even knew he existed." Infinitesimal is derived from the root infinite, which usually conjures up thoughts of immeasurably large quantities or sizes. But in this case, infinite connotes something immeasurably small.
Vocabulary lists containing infinitesimal
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
“Discovering Infinitesimal Breaths” and “Gold Limaçons for Pythagorus” do something similar.
From Seattle Times • Dec. 8, 2016
Infinitesimal radioactive isotopes can be carried along on the breeze, landing unseen on the ground, clothes and skin.
From Scientific American • Mar. 18, 2011
Infinitesimal traces of gunpowder components left on the hand by explosion gases show up unmistakably under neutron analysis.
From Time Magazine Archive
Not many years can pass away before the same curiosity excited by one of Perkins's Tractors will be awakened at the sight of one of the Infinitesimal Globules.
From Medical Essays, 1842-1882 by Holmes, Oliver Wendell
I think I have a slight remembrance of some infinitesimal sum you mentioned the first evening—" "Infinitesimal!
From A Cry in the Wilderness by Waller, Mary E. (Mary Ella)
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
