# semaphore

> English word · Noun · IPA /ˈsɛm.əˌfɔː/ · frequency rank #50,220

## Definitions
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.
2. 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.
3. 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.

## 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.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/semaphore