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)