Look up semaphore in Wiktionary, the free dictionary.

Semaphore is the use of an apparatus with telegraphy to create a visual signal transmitted over long-distances.

It may refer more specifically to:

• Flag semaphore
• Semaphore telegraph, a system of long-distance communication based on towers with moving arms
• Railway semaphore signal for railway traffic control
• Traffic semaphore, another name for automotive traffic lights based on their early resemblance to railway semaphores
• Turning semaphore or trafficators, retractable arms to indicate turns on automobiles from the 1920s to 1950s