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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)

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

Considering reidentification risk—and associated costs—alongside accuracy could help in more holistically assessing epsilon.

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

Analysts widely credit Publicis’ $3.7 billion acquisition of Sapient, closed in 2015, and its $4.4 billion purchase of data business Epsilon in 2019 with helping the French advertising company revive its fortunes.

From The Wall Street Journal ● Mar. 20, 2026

Named Epsilon Indi, the star is the smallest and coolest dwarf star yet observed with solar-like oscillations -- "starquakes" like those shown by the Sun.

From Science Daily ● Mar. 26, 2024

The Sigma Alpha Epsilon Fraternity Service Center, in a statement to WBRC, said the national organization is investigating what happened at the Alabama chapter and is cooperating with the university and law enforcement investigation.

From Seattle Times ● Sep. 24, 2023

“There were not any decent Experts until the removal of the Epsilon an entire unit ago. Let us hope these have impeccable knowledge and compliance.”

From "The Last Cuentista" by Donna Barba Higuera