Omicron

Omicron is the fifteenth letter of the Greek alphabet. It looks like a small "O" and is used in many areas, such as science and math. The letter Omicron comes from an old writing system called Phoenician and has been used for thousands of years.

In ancient times, Omicron made a specific sound, but today it is pronounced the same as the letter Omega in modern Greek. This letter also helped create other letters we use today, like the Roman letter O and some Cyrillic letters.

Omicron has a special meaning in counting systems too. When people use Greek letters to count, Omicron stands for the number 70. Its name changed over time to help tell it apart from the letter Omega, which is sometimes called the "big o."

Use

Omicron is the fifteenth letter of the Greek alphabet. It is also used in science and math, but it can be confusing because it looks like the Latin letter "o" and the number "zero".

In math, a symbol called big-O was created in 1894. Some people thought it looked like a capital Omicron letter.

In ancient Greece, omicron was used for the number 70. It also meant the fifteenth place in lists using Greek letters.

In astronomy, omicron names the fifteenth brightest star in a group of stars called a constellation. Examples include Omicron Andromedae, Omicron Ceti, and Omicron Persei.

The World Health Organization uses Greek letters to name important changes in the SARS‑CoV‑2 virus, which causes COVID‑19. In November 2021, they named a new version B.1.1.529 as Omicron.

Main article: Greek numerals

Main article: SARS-CoV-2 Omicron variant

History

In the oldest Greek writings, there were only five vowel letters: A, E, I, O, and Y. Back then, the letter O stood for both short and long vowel sounds. Later, in classical Attic Greek, the three vowel sounds were shown in different ways. The letter O was used for the short sound, the new letter Ω stood for a long sound, and OY was used for another long sound.

The Greeks took the shape of the letter O from a Phoenician letter, but they did not use its Phoenician name. In classical Attic Greek, the name for O was the long version of its sound: οὖ. Over time, the differences between long and short vowel sounds faded, causing confusion between O and Ω. This led to the new names ὂ μικρόν ("small O") for O and ὦ μέγα ("great O") for Ω.

Mispronunciation

When the Omicron variant of COVID-19 first appeared, some people said its name wrong. They called it "Omnicron" because many English words start with "Omni-".

Unicode

Greek omicron / Coptic O

• U+039F Ο GREEK CAPITAL LETTER OMICRON (Ο)
• U+03BF ο GREEK SMALL LETTER OMICRON (ο)
• U+2C9E Ⲟ COPTIC CAPITAL LETTER O
• U+2C9F ⲟ COPTIC SMALL LETTER O

These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style:

• U+1D6B6 𝚶 MATHEMATICAL BOLD CAPITAL OMICRON
• U+1D6D0 𝛐 MATHEMATICAL BOLD SMALL OMICRON
• U+1D6F0 𝛰 MATHEMATICAL ITALIC CAPITAL OMICRON
• U+1D70A 𝜊 MATHEMATICAL ITALIC SMALL OMICRON
• U+1D72A 𝜪 MATHEMATICAL BOLD ITALIC CAPITAL OMICRON
• U+1D744 𝝄 MATHEMATICAL BOLD ITALIC SMALL OMICRON
• U+1D764 𝝤 MATHEMATICAL SANS-SERIF BOLD CAPITAL OMICRON
• U+1D77E 𝝾 MATHEMATICAL SANS-SERIF BOLD SMALL OMICRON
• U+1D79E 𝞞 MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL OMICRON
• U+1D7B8 𝞸 MATHEMATICAL SANS-SERIF BOLD ITALIC SMALL OMICRON