sem·​a·​phore | \ ˈse-mə-ˌfȯr How to pronounce semaphore (audio) \

Definition of semaphore

 (Entry 1 of 2)

1 : an apparatus for visual signaling (as by the position of one or more movable arms)
2 : a system of visual signaling by two flags held one in each hand


semaphored; semaphoring

Definition of semaphore (Entry 2 of 2)

transitive verb

: to convey (information) by or as if by semaphore

intransitive verb

: to send signals by or as if by semaphore

Illustration of semaphore

Illustration of semaphore


semaphore 2: alphabet; 3 positions following Z: error, end of word, numerals follow; numerals 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 same as A through J

In the meaning defined above

Examples of semaphore in a Sentence

Recent Examples on the Web: Noun Predictably, this area was a resource locked with a mutex semaphore. Jacek Krywko, Ars Technica, "Definitely not Windows 95: What operating systems keep things running in space?," 2 Oct. 2020 The dollar, which has fallen by 6% against a basket of currencies since March, is usually part of the semaphore. The Economist, "Buttonwood The reasons behind the spectacular rally in metal prices," 11 June 2020 One dancer executed a series of semaphore-like movements, which the dancer on the next roof over tried to copy exactly, and so on down the line. Brian Seibert, New York Times, "A Home Version of Trisha Brown’s ‘Roof Piece,’ No Roof Required," 7 Apr. 2020 Giotto’s figures make simple, resonant gestures that are at once hauntingly isolated — like private semaphores — and vital markers in an unfolding communal narrative. Washington Post, "Bathers With a Turtle, 1907-08," 26 Feb. 2020 The truck hit the rear of the car, rolled onto its side, left the road and hit a semaphore light. Nick Ferraro, Twin Cities, "State Patrol investigating crash that killed 22-year-old woman in Inver Grove Heights; second fatality at intersection since mid-August," 3 Oct. 2019 Some of our fleeing units had hauled even more frozen Russian bodies out of the woods and propped them upright, their arms stilled in various eerie semaphore. Arna Bontemps Hemenway, The Atlantic, "Wolves of Karelia," 19 July 2019 At their disposal are agreed-upon symbols and semaphores. Rick Paulas, Popular Mechanics, "The Graffiti That Will Save Your Life," 22 Feb. 2016 Customers should be advised to bring semaphores in order to gain the attention of the waitstaff, which seems unaccustomed to any action at all and slightly bemused to encounter actual humans in their midst. Fox, Town & Country, "A Table for Mr. Fox," 21 Nov. 2012 Recent Examples on the Web: Verb The movie needs Winslet and Ronan’s skills, their ability to semaphore more with sliding glances and tiny gestures than many actors manage with pages of dialogue. Jeannette Catsoulis, New York Times, "‘Ammonite’ Review: Love on the Rocks," 12 Nov. 2020 One of the many things the halted meteorological data gathering couldn’t do on such occasions was release the mutex semaphore to the high-priority bus management task. Jacek Krywko, Ars Technica, "Definitely not Windows 95: What operating systems keep things running in space?," 2 Oct. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'semaphore.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of semaphore


1815, in the meaning defined at sense 1


1838, in the meaning defined at transitive sense

History and Etymology for semaphore


Greek sēma sign, signal + International Scientific Vocabulary -phore

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Time Traveler for semaphore

Time Traveler

The first known use of semaphore was in 1815

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Cite this Entry

“Semaphore.” Dictionary, Merriam-Webster, Accessed 25 Feb. 2021.

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More Definitions for semaphore



English Language Learners Definition of semaphore

: a system used for sending signals by using two flags that are held in your hands


sem·​a·​phore | \ ˈse-mə-ˌfȯr How to pronounce semaphore (audio) \

Kids Definition of semaphore

1 : a device for sending signals that can be seen by the receiver
2 : a system of sending signals with two flags held one in each hand

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