Definition of semaphore in US English:



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

    ‘if you learn semaphore or the Morse code, you'll have a fun way to send messages’
    • ‘The varied orientations of tiny fold patterns in the smallest grid boxes recall semaphore flags or suggest LED elements in a Times Square news zipper - except never in a hue as garish as red.’
    • ‘They will also be resurrecting the old semaphore in the grounds of Fort Selwyn in a daily demonstration to honour the Chappe brothers, who caused a sensation with the first commercial semaphore system near Paris.’
    • ‘Devices like this were not some kind of semaphore code, but simple, effective images that we could easily respond to.’
    • ‘They rely on team-mates at the other end to direct them, using highly untechnical language plus a kind of bowling semaphore for the hard-of-hearing.’
    • ‘Mobile phone users had no greater incidence of cancer of the brain than did people who communicated by only using semaphore flags or pushing notes in forked sticks carried by native runners.’
    • ‘It blinked in binary and semaphore, and clattered in Morse code.’
    • ‘Rochlitz doesn't know what to do with the chorus, who strut in formation and communicate in semaphore, though he is insightful when it comes to the principals.’
    • ‘She can calculate the location of a missing ice cream man from hints in photographs, she can build an action figure replica of her father from scratch, and she can use semaphore to pass messages between two feuding brothers.’
    • ‘You can operate an optical telegraph as used in the Napoleonic wars, crank up second world war field telephones and learn to read Morse and semaphore.’
    • ‘The signalling system is being upgraded from the mechanical semaphore system to a modern computerised one.’
    • ‘I have stood on the shed and waved my arms about the place making ham-fisted attempts at semaphore.’
    • ‘Use of semaphore flags was limited to within range of telescopes in earlier days and binoculars today.’
    • ‘This was thanks largely to what the East Germans called ‘stepped steering’, which appeared to communicate direction to the wheels by some sort of vague semaphore system.’
    • ‘Chappe moved to a secure semaphore system (the Chappe code assigns numbers to flag positions; the meaning of these numbers is known only to those in charge).’
    • ‘Throwing the balls out to the players, they hold their hands in the air like a secret sporting semaphore.’
    • ‘Possession of these books allowed British ships or personnel placed ashore to read the signals being relayed by the semaphore stations, which frequently included operational tasking to French fleet units.’
    • ‘Theft of the enemy's semaphore codebooks became an important part of the business of war.’
    • ‘Getting changed after swimming (it's got easier again, but I still must look like someone doing semaphore underwater), and a dad comes in with his two children - who are both girls.’
    • ‘Mr Emergency finally arrives after frantic hand signals from me from afar whilst still talking to him on the mobile. Good job he didn't understand semaphore.’
    • ‘The development of spin off technologies, such as the telegraph and semaphore flags, linked Civil War commanders on the first information net.’
    1. 1.1 An apparatus for sending messages by semaphore, consisting of an upright with movable parts.
      • ‘Pebble hides the details of interrupts from higher-level components and uses only semaphores for synchronization.’
      • ‘Like semaphores signaling an ambiguous statement, the chairs face away from the figures in the penultimate picture and virtually disappear in the varnished penumbra that concludes the final work of the cycle.’
      • ‘The protocol stack has to be ported to the OS; the Bluetooth solution generally takes five days or less and requires the following OS resources: 2 semaphores, 1 timer, and 1 event flag.’
      • ‘She fans her movements outward toward the sides of the body like a semaphore of swooping and crumpling limbs.’
      • ‘As they both maintain a tenacious grip on the receiver and attempt to get it away from the other, their arms swing from side to side like a signaling semaphore.’
    2. 1.2 A set of gestures intended to convey a message.
      ‘I saw Edward jumping up and down, performing an elaborate semaphore with his hat’
      • ‘Only three operations may be performed on a semaphore, all of which are atomic: initialize, decrement, and increment.’
      • ‘Sometimes I think of people as solitary automatons, sending out messages like semaphores that read: help.’


[with object]
  • Send (a message) by semaphore or by signals resembling semaphore.

    ‘Josh stands facing the rear and semaphoring the driver's intentions’
    • ‘He does so, prompting the linesman to semaphore the word ‘offside’ with his arresting flag.’
    • ‘He semaphores his designerlyness by wearing flouncy shirts and exuding a faint whiff of camp.’
    • ‘One could say the word ‘red’ aloud, or semaphore it from a cliff, or send it in Morse code, or write the French word ‘rouge’ on a blackboard, or point to a color chip.’
    • ‘I'm speaking of Kelly's movie personality, as semaphored by his body language, and perhaps as filtered not by the age that he emerged from but by the one that followed him.’
    • ‘The only part that seemed alive was the eyes, bright blue - too blue - and in constant motion, so that they seemed to be semaphoring some sort of secret coded message: first all blue, then milky white, then blue again.’


Early 19th century (denoting a signaling apparatus): from French sémaphore, formed irregularly from Greek sēma ‘sign’ + -phoros.