Mathematical Double-Struck Capital X 𝕏

Visual Description: The double struck X is a stylized X with extra vertical strokes. It looks bold, almost chalky, like a blackboard letter. The extra lines give it a sense of weight and distinction in math text. In digital fonts it reads clearly and acts as a special symbol.

Meaning & Usage: It serves as a decorative variant of X used to mark a particular mathematical object or variable. It is not a standard operator, but scholars may adopt it to emphasize a named space, a set, or a distinguished element in formulas. In software it labels special cases.

Historical Background: This style grew from the tradition of blackboard bold lettering. In digital typesetting, double struck letters were added to mathematical fonts to distinguish important objects from ordinary variables. Over time, math texts and calculators adopted the form as a visual cue for special status while keeping the X shape familiar.

Practical Use: In formulas and on calculators, the symbol can mark a special variable or a labeled space you want to keep distinct. Designers and educators use it in quick UI controls to indicate a special case or to compare objects with a clear visual hint. It helps readers scan results quickly.

See our category page for related symbols.

Look‑alikes: X (U+58).

Need styled alternatives? Try the Fancy Text tool.