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• epsilon
  epsilon

  noun

  the fifth letter of the Greek alphabet (E, ε).
• Epsilon
  Epsilon

  noun

  (foll by the genitive case of a specified constellation) the fifth brightest star in a constellation

epsilon

American  

[ep-suh-lon, -luhn, ep-sahy-luhn] / ˈɛp səˌlɒn, -lən, ɛpˈsaɪ lən /

noun

1. the fifth letter of the Greek alphabet (E, ε).

2. the consonant sound represented by this letter.

3. Mathematics. an arbitrarily small quantity, used to indicate that a given quantity is small, or close to zero.

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Epsilon ¹ British  

/ ˈɛpsɪˌlɒn, ɛpˈsaɪlən /

noun

1. (foll by the genitive case of a specified constellation) the fifth brightest star in a constellation

   Epsilon Aurigae

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epsilon ² British  

/ ˈɛpsɪˌlɒn, ɛpˈsaɪlən /

noun

1. the fifth letter of the Greek alphabet (Ε, ε), a short vowel, transliterated as e

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Etymology

Origin of epsilon

First recorded in 1400–50; from Greek e psīlón “bare, simple e ” (as opposed to diphthongal spellings which in later Greek represented the same sound)

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Example Sentences

See Examples For:

epsilon Epsilon

For the three stars with detected astrospheres, named 70 Ophiuchi, epsilon Eridani, and 61 Cygni, the researchers estimated their mass loss rates to be 66.5±11.1, 15.6±4.4, and 9.6±4.1 times the solar mass loss rate, respectively.

From Science Daily ● Apr. 12, 2024

Census data are used for many different analytical purposes with varying levels of aggregation, however, and any single choice of how to allocate epsilon will favor some scenarios over others.

From Slate ● Aug. 12, 2021

A few others made the rogue’s gallery of variants: gamma, beta, epsilon.

From Washington Post ● Aug. 8, 2021

Another delta mutation — also found in kappa and epsilon — is called L452R.

From Salon ● Jul. 29, 2021

There were five city quarters, designated by the Greek letters alpha through epsilon.

From "Circumference" by Nicholas Nicastro

The planet, known as Epsilon Indi Ab, is similar to Jupiter, yet its atmosphere appears more complex than expected.

From Science Daily ● Apr. 22, 2026

At the University of Miami, inside the columned fraternity house of Sigma Alpha Epsilon, one brother had some valuable information.

From The Wall Street Journal ● Mar. 6, 2026

Polymarket invited a delegation of fraternity brothers from Columbia University’s Sigma Phi Epsilon chapter to visit the company’s Manhattan headquarters on Nov. 16.

From The Wall Street Journal ● Mar. 6, 2026

Besides making traditional ads, Publicis is well invested in data and tech through its units Epsilon and Sapient, which employ online consumer data to help clients build marketing strategies.

From Reuters ● Oct. 12, 2023

When Sasha came home for vacation, they proudly wore an Epsilon Theta sweatshirt.

From "The 57 Bus" by Dashka Slater

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