What does "semaphore" mean?
Any equipment used for visual signalling by means of flags, lights, or mechanically moving arms, which are used to represent letters of the alphabet, or words.
Semaphore
/ˈsɛm.əˌfɔː/ noun, verb
noun, verb ·Moderate ·College level
Meaning at a glance
- Primary sense: Any equipment used for visual signalling by means of flags, lights, or mechanically moving arms, which are used to represent letters of the alphabet, or words.
- Grammar: semaphore is listed as noun, verb.
- Nearest alternatives: aid to navigation, alarm, amber light, balefire.
- Useful contrasts: no signal, silence, uncoordinated access.
- Usage evidence: Today we're going to make a semaphore to control access to our variable by different threads.
How to use "semaphore"
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- Compare nearby synonyms to make sure "semaphore" carries the exact meaning, tone, and strength you need.
- Use the example sentence as a context check. If your sentence uses the word differently, confirm that the grammar still fits.
Meaning check
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- Does it match the intended tone rather than only the dictionary definition?
- Would a simpler synonym be clearer for the reader?
- Is there enough surrounding context to prevent ambiguity?
Source and review context
This entry combines structured lexical data with WordToolSet review checks. Definitions, examples, synonyms, and usage notes may come from different source tables, so the page is designed to show evidence from more than one angle before you rely on "semaphore" in a final draft.
If a word has several senses, prefer the sense that matches your sentence's grammar and surrounding context. A correct definition can still be the wrong choice when the sentence needs a different register, emphasis, or level of specificity.
Before you rely on this definition
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Compare nearby meanings
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Definition decision workflow
1. Identify the role
Check whether "semaphore" is acting as noun, verb in your sentence. A definition is only useful when the grammar matches the way the word is being used.
2. Test the nearest option
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3. Confirm with context
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Final meaning check
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When the definition, synonym evidence, and example context point in the same direction, the word is usually a safer choice. When they conflict, revise the sentence or choose a clearer alternative.
Definitions
Noun
- 1 Any equipment used for visual signalling by means of flags, lights, or mechanically moving arms, which are used to represent letters of the alphabet, or words. countable, uncountable
"We must here take the liberty of expostulating with Sir Home [Riggs] Popham and the first Lord of the Admiralty, for having given to the telegraphic machine, invented by that gallant officer, the barbarous name of Semaphore, instead of Sematophore or Semophore—either of them ugly enough."
- 2 an apparatus for visual signaling with lights or mechanically moving arms wordnet
- 3 A visual system for transmitting information using the above equipment; especially, by means of two flags held one in each hand, using an alphabetic and numeric code based on the position of the signaller's arms; flag semaphore. countable, uncountable
"Its [the article's] object is to furnish a rule for determining the number of distinct signals which can be made by any semaphore, whatever be the number of arms or indicators, of whatever be the number of positions of each arm. In the Cyclopædia of Rees, the number of signals which the semaphores of the line of communication between Paris and Landau were capable of making, is stated to be 823,543, which is no less than 1,274,608 fewer than the real number, an error not arising from the press, but from the principle of computation."
- 4 A bit, token, fragment of code, or some other mechanism which is used to restrict access to a shared function or device to a single process at a time, or to synchronize and coordinate events in different processes. countable, uncountable
"The thread increments the semaphore to prevent other threads from entering the critical section at the same time."
Verb
- 1 To signal using, or as if using, a semaphore, with the implication that it is done nonverbally. ambitransitive, figuratively
"The person intending to Semaphore will make the International Code Signal VOX (I am going to Semaphore to you), and set his Semaphore at the alphabetical sign [...] with the Indicator out, and wait until the person to whom the Semaphore signal is to be made hoists his answering pennant close up. [...] The British method of Semaphoring by flags held in the hand which is shown in plate VIII is exactly the same as the British Movable Semaphore system, which has just been explained, the positions of the apparatus which denote the letters, numbers, and special signs being, it will be seen, identical in each case, and the only difference being in the apparatus employed."
- 2 convey by semaphore, of information wordnet
- 3 send signals by or as if by semaphore wordnet
Synonyms
All synonymsAntonyms
Example
"Today we're going to make a semaphore to control access to our variable by different threads."
Common questions
What is a synonym for "semaphore"?
Common synonyms include: aid to navigation, alarm, amber light, balefire, beacon, beacon fire.
How do you use "semaphore" in a sentence?
Today we're going to make a semaphore to control access to our variable by different threads.
How do you pronounce "semaphore"?
Pronounced /ˈsɛm.əˌfɔː/.
Etymology
The noun is borrowed from French sémaphore, from Ancient Greek σῆμα (sêma, “mark, sign, token”) + French -phore (from Ancient Greek -φόρος (-phóros, suffix indicating a bearer or carrier)). By surface analysis, sema- + -phore. The verb is derived from the noun.