What 𝐢 means
In Word, type 1D422 and press AltX.
What does bold i mean?
It is lowercase i in a distinct mathematical bold alphabet.
Mathematical letter styles can distinguish variables rather than decorate them. In physics and applied math, bold lowercase letters commonly stand for vectors, but the surrounding formula tells you what 𝐢 means here.
Printed formulas used typographic styles to distinguish variables before Unicode encoded these styles as separate plain-text characters. Mathematical alphabets are meant for mathematical or technical notation; use ordinary text formatting for bold emphasis in prose.
Technical and notation-specific; bold style can mark a distinct variable, and the formula supplies its role.
Changing it to plain i can erase a distinction the formula depends on.
Part of the collection
Don't confuse it with
2
Combination ideas
1Questions people ask
1Can text normalization turn 𝐢 into plain i?
Yes. Unicode's NFKC and NFKD normalization forms can map mathematical letter styles to plain Latin letters; normalization is a way to standardize text. That removes the bold distinction, so mathematical software must preserve the style when it carries meaning.
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12
How to type or find 𝐢
- Search it as
- bold i · bold small i · bold lowercase i · math bold i · unicode bold i
- Shows up in
- Anything that takes text · its shape is whatever your font draws
𝐢\1D4221D422 and press AltX; Word converts the hexadecimal value to 𝐢.𝐢 in HTML source to produce the character.\mathbf{i} in math mode for bold upright i; this is formatting markup, not the literal Unicode character.Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.