Translation guide
The English word "semaphore" refers to a system of sending signals using flags, lights, or arm positions. In Japanese, the most common equivalent is 手旗信号 (tebata shingō) for flag semaphore, but the term can also refer to railway signals or, in computing, a synchronization mechanism. This guide covers the main meanings and their natural Japanese expressions.
To refer to the system of communicating over a distance by holding flags in specific positions.
The standard term for flag semaphore. Literally 'hand-flag signaling'. Used in contexts like maritime communication or scouting.
彼は手旗信号でメッセージを送った。
He sent a message by semaphore.
Katakana loanword from English. Used in technical or modern contexts, but less common than 手旗信号 for traditional flag signaling.
セマフォア信号は海上で使われる。
Semaphore signals are used at sea.
Literally 'flag-waving signal'. An older or more descriptive term, sometimes used historically.
昔、旗振り信号で情報を伝えた。
In the old days, they conveyed information by semaphore.
To refer to the mechanical signal with a moving arm used on railways.
The standard term for a railway semaphore signal. Literally 'arm-wood-type signal device'.
その駅にはまだ腕木式信号機が残っている。
That station still has a semaphore signal.
Katakana term used in railway contexts, often alongside 腕木式信号機.
セマフォア信号は次第に色灯信号に置き換えられた。
Semaphore signals were gradually replaced by color light signals.
To refer to a variable used to control access to a common resource in concurrent programming.
The standard computing term, a direct loanword from English. Used in programming and operating systems.
このプログラムはセマフォを使って排他制御を行っている。
This program uses semaphores for mutual exclusion.
Alternative katakana spelling, sometimes used in older texts.
セマフォアは並行処理の基本概念だ。
Semaphores are a fundamental concept in concurrent processing.
手旗信号 is the native Japanese term for flag semaphore and is widely understood. セマフォア is a loanword that can refer to the general concept but is less common in everyday language. For railway signals, 腕木式信号機 is the precise technical term, while セマフォア信号 is also used.
If you are talking about programming, always use セマフォ. For historical or maritime flag signaling, 手旗信号 is the best choice. Avoid using 手旗信号 for computing contexts.