Omicron Symbol
About Omicron Symbol
Ο is the Omicron Symbol, the fifteenth letter of the Greek alphabet in its uppercase form. Ο is the literal small o; its lowercase became widely known through COVID-19 variant naming and also appears in big-O notation.
【Pronunciation】 In English, Ο is most often pronounced OM-ih-kron (IPA: /ˈɒmɪkrɒn/). This is simply the anglicized name of the Greek letter.
The uppercase Omicron Symbol Ο is written as a distinct capital Greek glyph and is assigned codepoint U+039F in the Greek and Coptic Unicode block. In plain or sans-serif fonts it can be mistaken for the Latin letter O, so verify the typeface or context.
【Historical Origin】 Like every Greek letter, Ο was adapted from a Phoenician consonant and entered mathematical and scientific notation through the work of ancient Greek scholars, remaining in continuous use to the present day.
【Common Uses】 Ο is highly active across disciplines and frequently appears alongside other Greek capitals such as Δ (Δ), Σ (Σ), Π (Π) and Ω (Ω) in formulas, papers, and engineering drawings. Its clear shape and long tradition make it a standard symbol in many fields.
How to Type Omicron Symbol
Windows Input
Method 1: Hold Alt and type 927 on the numeric keypad, then release Alt to get Ο.
Mac Input
Method 2: Press Control + Command + Space to open the Character Viewer, search for "greek" or "Omicron Symbol", then select Ο.
HTML/CSS Input
HTML: Ο or Ο; CSS: content: "\039F";
LaTeX Input
The capital Omicron Symbol Ο has no dedicated LaTeX command because it is identical to the Latin capital O; simply type O in math mode to produce Ο.
Omicron Symbol FAQ
How is Ο pronounced?
The English pronunciation of Ο is OM-ih-kron (IPA: /ˈɒmɪkrɒn/). It is the anglicized name of the Greek letter, used directly rather than described as "uppercase Ο".
What is the difference between Ο and the Latin letter O?
Ο (U+039F) is a Greek capital letter, whereas O is a Latin letter; their codepoints and glyphs differ. In a proper typeface Ο and O are clearly distinct, but in plain text or sans-serif fonts they can be confused, so rely on context.
How do I type Ο in Word, web pages, and LaTeX?
On Windows use Alt+927 on the numeric keypad; on Mac open the Character Viewer and search "greek" or "Omicron Symbol"; on the web use the HTML entity Ο; in LaTeX simply type the letter O.