[ep-suh-lon, -luhn or, esp. British, ep-sahy-luhn]
the fifth letter of the greek alphabet (E, ε).
the consonant sound represented by this letter.
Mathematics. an arbitrarily small quantity, used to indicate that a given quantity is small, or close to zero.

< Greek è psīlón bare, simple e (as opposed to diphthongal spellings which in later Gk represented the same sound)

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World English Dictionary
epsilon (ˈɛpsɪˌlɒn, ɛpˈsaɪlən)
the fifth letter of the Greek alphabet (Ε, ε), a short vowel, transliterated as e
[Greek e psilon, literally: simple e]

Epsilon (ˈɛpsɪˌlɒn, ɛpˈsaɪlən)
(foll by the genitive case of a specified constellation) the fifth brightest star in a constellation: Epsilon Aurigae

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
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Word Origin & History

from Gk., lit. e psilon "bare -e-, -e- and nothing else," in contradistinction to the diphthong -ai-, which has the same sound.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

epsilon ep·si·lon (ěp'sə-lŏn', -lən)

  1. Symbol ε The fifth letter of the Greek alphabet.

  2. The fifth in a series.

  1. Of or relating to the fifth member of a particular ordered set.

  2. Relating to or characterizing a polypeptide chain that is one of five types of heavy chains present in immunoglobins.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Computing Dictionary

EPSILON definition

A macro language with high level features including strings and lists, developed by A.P. Ershov at Novosibirsk in 1967. EPSILON was used to implement ALGOL 68 on the M-220.
["Application of the Machine-Oriented Language Epsilon to Software Development", I.V. Pottosin et al, in Machine Oriented Higher Level Languages, W. van der Poel, N-H 1974, pp. 417-434].
[Jargon File]

epsilon definition

1. The fifth letter of the Greek alphabet.
2. (From the Hungarian mathematician Paul Erdos) A very small, insignificant, or negligible quantity of something.
The use of epsilon is from the epsilon-delta method of proof in differential calculus.
The Free On-line Dictionary of Computing, © Denis Howe 2010 http://foldoc.org
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Encyclopedia Britannica


(symbol e), fundamental physical constant expressing the naturally occurring unit of electric charge, equal to 1.6021892 1019 coulomb, or 4.80325 1010 electrostatic unit (esu, or statcoulomb). In addition to the electron, all freely existing charged subatomic particles thus far discovered have an electric charge equal to this value or some whole-number multiple of it. Quarks, which are always bound within larger subatomic particles such as protons and neutrons, have charges of 13 or 23 of this value

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
With this the annoying epsilon-delta limit argument is replaced by simple algebra.
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