signal/'sɪgnəl/

n. a sound or movement that gives information or tells sb to do sth

v. give a signal to sb/sth

n. [C] 信号；暗号：Run when you hear the signal. 听到信号后就跑。

◇[signal (for sb) to do sth] Mr. Smith gave her the signal to leave the table. 史密斯先生暗示她下桌。

◇a warning signal 警告信号

◇TV signals 电视信号

v. （向…）发信号：[signal (sth) to sb] A man in the distant is signaling to us. 远处一个男子在向我们示意。

◇signal a warning to him 向他发出警示信号

◇The ship signalled for help. 这艘船发了求救信号。

◇[signal (to) sb to do sth] He signaled the car to stop by waving his hands. 他挥舞双手示意车停下来。

构词sign + -al

辨析sign; signal; symbol