semaphore

Concise Oxford English Dictionary © 2008 Oxford University Press:
semaphore/ˈseməfɔː(r)/

▶noun

• 1 a system of sending messages by holding the arms or two flags or poles in certain positions according to an alphabetic code.

• 2 an apparatus for signalling in this way, consisting of an upright with movable parts.

▶verb send by semaphore or by signals resembling semaphore.

– derivatives
semaphoric adjective,
semaphorically adverb.

– origin C19: from Fr. sémaphore, formed irregularly from Gk sēma ‘sign’ + -phoros.