Semaphore (noun)

1. A system of sending messages using flags or lights, typically as visual signals from one ship to another or from a stationary location to a moving object such as a train.
2. An object, such as a flag or a light, used in semaphore signaling.

Origin:

Derived from the greek word 'sema' meaning 'sign' and the greek word 'pherein' meaning 'to carry'.

Examples:

1. In the past, ships used semaphore to communicate with each other while at sea.
2. The railway worker signaled the incoming train by using semaphore flags.
3. The semaphore system was used extensively in the military to send messages quickly over long distances.
4. The semaphore tower was a critical component of the communication network along the coast.
5. Semaphore signaling was replaced by telegraphs and radios in the 19th and 20th centuries, but it is still used in some specialized situations.