What 𝐦 means
No; the formula or its notation key decides. In physics and applied math, bold lowercase letters commonly mark vectors—quantities with magnitude and direction—so 𝐦 may be a vector there. A writer can use bold m for another variable, so check the formula's definitions.
Boldface became a practical vector mark: vectors have magnitude and direction, while scalars are ordinary number-like quantities. Maxwell promoted blackletter (Fraktur) for vectors in 1873; in 1886, Oliver Heaviside used bold Clarendon type, a heavy serif face, because it was easier to read in formulas. A Unicode proposal in 1999 called for separate plain-text characters for mathematical styles so the distinctions between variables would survive.
In formulas, boldface can distinguish a variable; for ordinary emphasis, use formatting on a regular m.
Don't infer “vector” from bold alone; check the formula's definitions.
Don't confuse it with
1Questions people ask
1Why did 𝐦 turn into plain m?
A Unicode cleanup step called NFKC can fold 𝐦 to plain m and erase the bold distinction. That can change a formula if the letter style separates variables.
How to type 𝐦
𝐦\1D426Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.