What 𝕞 means
In a formula, 𝕞 is a lowercase m in blackboard-bold style.
The double strokes can distinguish it from ordinary m; the formula’s definition tells you what it stands for.
Blackboard bold grew from a chalkboard workaround: when bold chalk was unavailable, writers doubled selected strokes to make letters stand out. The handwritten convention later moved into print. Older books often used plain or bold capitals for many of the same set names; the style became a way to distinguish mathematical symbols, and the expanded lowercase alphabet extends it to letters such as m.
Can formatting turn 𝕞 back into plain m?
Yes, compatibility normalization can erase the distinction. Unicode’s NFKC form folds mathematical letters to plain letters, so 𝕞 becomes m. That can help text matching, but it can change a formula’s meaning. NFC keeps the distinction.
In a formula, the double strokes mark a deliberate mathematical notation choice.
NFKC can flatten 𝕞 to ordinary m and erase a distinction the formula may need.
Part of the collection
Don't confuse it with
4
Questions people ask
1Why does 𝕞 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.
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11
How to type or find 𝕞
- Also called
- blackboard-bold m · double-struck m
- Search it as
- blackboard bold m · double struck m · mathbb m · mopf · fancy m · styled m
- Shows up in
- Anything that takes text · its shape is whatever your font draws
𝕞\1D55E𝕞 represents 𝕞; it is not a shortcut in ordinary text fields.1D55E without U+, then press Alt+X. If it shows as a box, choose a font that includes the glyph.Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.