Prohibited Sign

The circle-slash no sign marks its target as forbidden. Alone, it reads as a firm no or ban; the target comes from surrounding words, a nearby pictogram, or the conversation.

A real-world sign usually puts the slash over an action pictogram. In text, 🛇 sits beside its target instead: 🛇🚬 reads as no smoking, with the cigarette still visible. A 1998 study noted that a slash can obscure pictogram details, so the banned action needs to remain recognizable.

Use it for a clear veto or rule. If the boundary matters, name the action in words; alone, 🛇 can sound more final than you mean.

Where did the prohibition sign come from?

Its international road-sign form emerged through European standardization.

The documented road-sign lineage passed through European work in 1926, 1928, and 1931. Proposals in 1928 used a red circle to mean passage prohibited; the 1931 Geneva Convention harmonized the system so traffic rules could travel across language barriers.

The generic mark signals that an action is prohibited; nearby text or a pictogram names the action. A 1998 review traced the red circle-slash from Europe into use in the United States and elsewhere. In a message, the same rule-like sign leaves the target to context.