epsilon

Etymology

It is borrowed from Ancient Greek ἒ ψιλόν (è psilón, “bare e, simple e”),^{[2][3][4][5][6][1]} from the neuter of ψιλός (psilós, “bare, smooth, simple”).^[4][7] Late grammarians used the name for the short e, to set it apart from a diphthong that had come to have the same sound.^[3][2][8] The adjective is of uncertain origin;^[3] Etymonline reports that Watkins connects it with Proto-Indo-European *bhes- (“to rub”).^[3]

Earliest recorded meaning

The fifth letter of the Greek alphabet: about 1400, in Mandeville's Travels.^[2] Merriam-Webster Unabridged dates it to the 15th century,^[5] and the Shorter Oxford to the early 18th.^[9]

Semantic evolution

From 1842 astronomers used it, before the genitive of a constellation's Latin name, for the fifth brightest star in that constellation.^[2][9][6] In the 20th century it became an examiner's fifth-class mark (1907) and a name for a person of low intelligence, first in Huxley's Brave New World (1932).^[2] In mathematical analysis it stands for an arbitrarily small positive quantity.^[5]

Timeline

• c. 1400 – the fifth letter of the Greek alphabet.^[2]
• 1842 – in astronomy, the fifth brightest star of a constellation.^[2]
• 1907 – an examiner's fifth-class mark.^[2]
• 1932 – a person of low intelligence.^[2]

Meanings

Noun

1. The fifth letter of the Greek alphabet.^[5][6][2]
2. (astronomy) The fifth brightest star in a constellation.^[6][2][9]
3. (mathematics) An arbitrarily small positive quantity.^[5]
4. An examiner's fifth-class mark.^[2][9]

Word family

• epsilonic

Related words

• upsilon

References

1. ^ a b c Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
5. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
6. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins
7. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
8. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
9. ^ a b c d Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press