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[om-i-kron, oh-mi-] /ˈɒm ɪˌkrɒn, ˈoʊ mɪ-/
the 15th letter of the Greek alphabet (O, o).
the vowel sound represented by this letter.
Origin of omicron
< Greek ō mikrón, literally, small o. Cf. omega Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for omicron
Historical Examples
  • Mira, (omicron Ceti,) in the neck of the Whale, is a variable star.

    Letters on Astronomy Denison Olmsted
  • Newton presented him with one of his publications, entitled "omicron."

  • At all events, it was not possible for him to think of anything bad when he called “omicron.”

    Walter Pieterse Multatuli
  • omicron must show her face in the stars from time to time to remind the child of his love.

    Walter Pieterse Multatuli
  • And then, on the following morning, Sir omicron also went his way.

    Doctor Thorne

    Anthony Trollope
  • One of the most interesting of variable stars is that known as omicron Ceti, whose period of change is about 331 days.

    Aether and Gravitation

    William George Hooper
  • Another very interesting class of variables is known as the omicron Ceti type.

    Astronomy David Todd
  • The spectrum of omicron Ceti contains many very bright lines, and a large proportion of the variable stars are of this type.

    Astronomy David Todd
  • The fore-paws are drawn up to the breast and represented by the stars Zi and omicron.

    Astronomy with an Opera-glass Garrett Putman Serviss
  • I have not read them regularly through, but sufficiently to observe that they are much indebted to omicron.

British Dictionary definitions for omicron


/əʊˈmaɪkrɒn; ˈɒmɪkrɒn/
the 15th letter in the Greek alphabet (Ο, ο), a short vowel, transliterated as o
Word Origin
from Greek ō mikron small o; see micro-, omega
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for omicron

15th letter of the Greek alphabet, literally "small 'o,' " from Greek (s)mikros "small," from PIE *smik-. Because the vowel was "short" in ancient Greek. Cf. Omega.

Online Etymology Dictionary, © 2010 Douglas Harper
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omicron in Medicine

omicron om·i·cron (ŏm'ĭ-krŏn', ō'mĭ-)

Symbol o The 15th letter of the Greek alphabet.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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