Mathematical Double-Struck Small K 𝕜

Visual Description: A lowercase k with a double stroke. The glyph shows two parallel vertical lines through the stem, producing a bold, blackboard-like look. It sits with ordinary letters in formulas, but it reads as a special token. In calculators and math editors, you can insert it by a symbol picker or font option.

Meaning & Usage: Double-struck letters mark special mathematical objects. The double k indicates a distinct variable, a named space, or a particular family in a problem. Writers use it to distinguish from ordinary variables, and readers treat it as a symbol with dedicated meaning. In formulas, it signals emphasis or a specific role.

Historical Background: Origin lies in a handwritten convention used on blackboards to mark sets and special objects. Over time, printers and fonts adopted double-struck styles to keep that distinction in print and digital text. The idea carried into typesetting systems, where commands like math fonts or mathbb provide the same signal without ambiguity.

Practical Use: In practice, you type it by choosing a double-struck font in a math editor or by copying from a character palette. Many apps offer a symbol picker or keyboard shortcut. It helps with formulas, set membership, or comparisons, and it remains clear under a quick UI that highlights special tokens.

See our category page for related symbols.

Look‑alikes: k (U+6B).

Need styled alternatives? Try the Fancy Text tool.