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.
Washington’s manic quarantining of cruise-ship passengers, its restricting of foreign entry, probably did next to nothing to slow spread until a vaccine and the less-virulent omicron variants arrived, which took a year.
From The Wall Street Journal ● Aug. 7, 2026
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
That single-target vaccine replaced combination shots that had been targeting both the original coronavirus strain and a much earlier omicron version.
From Seattle Times ● Feb. 28, 2024
Zero never worked its way into ancient Western numbers, so it is unlikely that the omicron is the mother of our 0.
From "Zero: The Biography of a Dangerous Idea" by Charles Seife
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