A sign, signal, or cue used to indicate or prompt an action; a gesture or signal given to communicate timing or intent.
彼は手を振って合図した。
He waved his hand as a signal.
先生の合図で授業が始まった。
The lesson began at the teacher's cue.
信号が青に変わるのが渡る合図だ。
The light turning green is the signal to cross.
二人は目で合図を交わしてから演奏を始めた。
The two exchanged a glance as a cue and then started playing.