Mathematical Bold Capital E

In Word for Windows, enter 1D404, then press Alt+X. As of 2026, if other text touches the code, select only 1D404 before pressing the shortcut.

What does bold E mean in math?

It is a distinct math variable; the formula gives its meaning.

Bold letters often mark vectors in physics and engineering, but that is a notation convention, not a fixed definition for 𝐄. Other authors can assign bold letters different roles, so read the equation or its nearby definition.

Mathematical boldface came from typeset notation, where weight can identify a variable rather than decorate a letter. The Scientific and Technical Information eXchange (STIX), a collaboration among scientific publishers, began assembling the broad character set needed from manuscript through publication in 1995; the publishers later sponsored Unicode proposals for mathematical alphabets. These alphabets extend a smaller set of math-specific letterlike characters already present in older character sets, letting the distinction travel in plain text.