omicron
Americannoun
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the 15th letter of the Greek alphabet (O,o ).
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the vowel sound represented by this letter.
noun
Etymology
Origin of omicron
< Greek ō mikrón, literally, small o. Cf. omega
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
When the SARS-CoV-2 delta and omicron variants emerged in the spring and fall of 2021, mRNA vaccines became less effective in preventing infections.
From Salon • Sep. 5, 2025
A show-threatening omicron shutdown, illness and the loss of Adam, who passed away at the end of April 2023.
From Los Angeles Times • May 29, 2024
The researchers measured how many of the participants' neutralizing antibodies were specific for the original variant, the omicron variant or both.
From Science Daily • May 17, 2024
It also reduced viral loads in those infected by the alpha, delta or omicron coronavirus variants that caused distinct COVID-19 waves over the three years of the pandemic.
From Seattle Times • May 3, 2024
During the peak of ancient astronomy, Greek astronomical tables regularly employed zero; its symbol was the lowercase omicron, o, which looks very much like our modern-day zero, though it’s probably a coincidence.
From "Zero: The Biography of a Dangerous Idea" by Charles Seife
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
