What 𝑂 means
It has no fixed mathematical definition by itself.
The surrounding field decides what it names: it may be a variable or quantity. Scientific notation commonly uses italics for variables and quantities, while upright letters can mark units.
Mathematical italic grew from print conventions: Descartes established italic lowercase unknowns in 1637. A 1998 Unicode proposal argued that math styles distinguish symbols in plain text, so each style was encoded as its own character.
Part of the collection
Don't confuse it with
1
Related characters
2
Questions people ask
1Can 𝑂 turn into plain O?
Yes. NFKC, a Unicode text-normalization form, maps it to plain O and erases the italic distinction. This can affect formulas or searches that rely on the styled character.
More like this
11
How to type or find 𝑂
- Search it as
- math italic o · italic capital o · fancy o · unicode o
- Shows up in
- Anything that takes text · its shape is whatever your font draws
Windows (Word)
Windows
HTML
𝑂CSS
\1D442LaTeX math
Inside math mode, enter
\mathit{O} to typeset an italic capital O.HTML source
𝑂 is a numeric character reference for this exact character.Codes and encoding1 code points
HTML decimal
𝑂
HTML hex
𝑂
CSS content
content: "\1D442";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%F0%9D%91%82
1
On screen
1
Code points
2
JS .length
4
UTF-8 bytes
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.