eta

Etymology

It is borrowed from Ancient Greek ἦτα (êta),^[2][3][4][5] the name of the seventh letter of the Greek alphabet.^[2][5] Merriam-Webster and Webster's Third give the immediate source as Late Latin ēta.^[6][7] The Greek name comes from a Phoenician letter name,^[8][9][10] akin to that of the Hebrew letter heth;^{[10][6][11][5]} Etymonline notes that it was originally the name of the aspirate, the h sound.^[8] Klein explains the final -a as added because a Greek word cannot end in t, as in alpha.^[5]

Earliest recorded meaning

The name of the seventh letter (Η, η) of the Greek alphabet: about 1400, in Mandeville's Travels.^[2] Merriam-Webster dates it to the 15th century,^[6] and the Shorter Oxford to late Middle English.^[4]

Semantic evolution

The letter corresponds to English e and stands for a long vowel, transliterated e or ē.^[2][9][12] Written as the symbol η, it was later used in astronomy, from the late 18th century, for the seventh brightest star of a constellation,^[4] and in particle physics, from 1961, for a group of mesons with zero spin and isospin.^[2][4][13]

Timeline

• c. 1400 – the seventh letter of the Greek alphabet, in Mandeville's Travels.^[2]
• late 18th century – in astronomy, the seventh brightest star of a constellation.^[4]
• 1961 – in particle physics, the eta meson.^[2]

Meanings

Noun

1. The seventh letter of the Greek alphabet (Η, η), a long e sound.^[9][6][2]
2. In particle physics, an eta meson, a neutral meson with zero spin and isospin.^[2][4][13]
3. In astronomy, written η before the Latin name of a constellation: its seventh brightest star.^[4]

Word family

• eta meson

Related words

• etacism
• alpha
• heth

Usage notes

The usual British pronunciation is /ˈiːtə/, the usual American one /ˈeɪtə/.^[6][13] Dictionaries also record unrelated nouns of the same spelling: a word borrowed from Japanese for a member of an outcast class in Japan (from 1897),^[2][6][4] and the eta palm, a borrowing from Arawak (1769).^[2] ETA is also an abbreviation of "estimated time of arrival" (1939).^[2][9]

References

1. ^ 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. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
4. ^ a b c d e f g h Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b c d Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
6. ^ a b c d e f Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ Gove, Philip Babcock, ed. (1961), Webster's Third New International Dictionary of the English Language, Unabridged, Springfield, Mass.: G. & C. Merriam
8. ^ a b Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
9. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins
10. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
11. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
12. ^ Soanes, Catherine; Stevenson, Angus, eds. (2004), Concise Oxford English Dictionary, 11th ed., Oxford: Oxford University Press
13. ^ a b c Random House Webster's Unabridged Dictionary (1999), 2nd ed., New York: Random House