Mathematical Bold Small Z

As of 2026, Word for Windows converts 1D433 with Alt+X.

In HTML source, use 𝐳 as a numeric character reference. It produces the same character when the page's font supports it.

Does bold z always mean a vector?

No; in physics and applied math, bold lowercase letters often mark vectors.

A vector is a quantity with both size and direction. In a formula, 𝐳 can name one; its bold style separates it from a plain z, but it has no universal value. The surrounding notation tells you what it represents.

The convention has a practical backstory: in 1886, physicist Oliver Heaviside said he had adopted bold Clarendon type—a heavy, readable typeface—for vectors because Greek letters and Fraktur, an ornate blackletter style, were hard to distinguish in formulas. Unicode later gave mathematical styles separate letter characters so those distinctions could survive in plain-text equations.

Can text cleanup turn 𝐳 into plain z?

Yes; NFKC and NFKD cleanup can turn it into plain z.

NFKC and NFKD are Unicode text-normalization forms: they map mathematical style letters to their basic Latin letters, so 𝐳 becomes z. NFC and NFD preserve the distinction. Avoid NFKC or NFKD when the bold form carries meaning in an equation.