Mathematical Bold Capital Sigma

In Microsoft Word, type 1D6BA and press AltX; Microsoft documents this shortcut as of 2026-09-28. 𝚺 is the bold mathematical form of Greek capital sigma, and its role depends on the formula. Euler used plain Σ for summation in 1755; the dedicated sum operator is .

Text symbol

What 𝚺 means

It is the bold mathematical form of Greek capital sigma.

Math notation uses letter styles to distinguish symbols that could otherwise look alike. The bold style marks a distinct math letter, but it does not say what quantity 𝚺 names; read that from the formula.

Greek writers adapted their alphabet from Phoenician writing; sigma represented the Greek /s/ sound. Inscriptions show Greek alphabetic writing by the 8th century BCE. In Microsoft Word, type 1D6BA and press AltX; Microsoft documents this shortcut as of 2026-09-28.

Does 𝚺 mean a sum?

No; 𝚺 is a bold letter, not the sum operator.

Euler used the plain capital letter Σ for summation in 1755. The separate character is Unicode’s dedicated large operator for a sum, laid out with limits in mathematical notation. So bold 𝚺 does not automatically mean a sum; the formula’s notation decides its role.

Part of the collection

𝐁

Bold Letters (Bold Text)

Don't confuse it with

Greek Capital Letter Sigma

The plain Greek capital letter; it can be assigned a summation role in a formula, while 𝚺 is its bold mathematical form.

∑

N-Ary Summation

The dedicated summation operator, which can take limits in mathematical layout; it is a separate character from the bold sigma letter.

Questions people ask

Why did 𝚺 turn into Σ?

It can. NFKC or NFKD compatibility normalization folds mathematical letter styles back to ordinary Greek, so 𝚺 may become Σ and lose its bold distinction.