Bold Italic Partial Differential Sign

Enter 1D74F, then press Alt+X.

As of 2026-09-28, Word converts this hexadecimal value to the exact character. Styling ordinary ∂ in bold italics may look similar, but it remains a different Unicode character.

What does 𝝏 mean?

It marks a partial derivative: one input changes while others stay fixed.

For a function f(x,y), 𝝏f/𝝏x asks how f changes as x varies while y is held fixed. An author may use bold italic to distinguish symbols within a notation system; the surrounding formula tells you what distinction is intended.

The sign first separated two kinds of change

The sign’s recorded trail starts with Condorcet: in a 1770 paper published in 1773, he used ∂ for a partial difference beside d for a total differential. Legendre put it in the fraction ∂u/∂x in 1786 to separate partial change from total differential du/dx while studying maxima and minima in the calculus of variations, which asks which function makes a quantity largest or smallest. Legendre later stopped using it; Jacobi revived it in 1841 and used it extensively for partial differentials.