What ℴ means
It is a script o, not a fixed operator.
Its documented mathematical glosses are “order” and “of inferior order to.” In asymptotic notation, ordinary lowercase o means that f(x)/g(x) → 0 at the stated limit. That notation is written with a plain mathematical o, so ℴ is not an automatic substitute.
Is ℴ the same as ordinary o?
No: ℴ is a script character; o is the plain letter.
A font draws ℴ in a script style, so it may look close to ordinary o in some typefaces. In a formula, keep the distinction the notation uses.
Technical and typographic; in a formula, its role comes from the writer’s notation.
Do not replace the plain o in little-o notation with ℴ unless the notation calls for the script character.
Don't confuse it with
1Questions people ask
1Why does ℴ show as a box on some devices?
Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.
How to type ℴ
ℴ\2134Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.