/ˈsaɪrən ||; ˈsaɪrən/noun [C] a device that makes a long, loud sound as a warning or signal 汽笛；警报器: an air-raid siren 空袭警报器Three fire engines raced past, sirens wailing. 三辆消防车疾驶而过，一路鸣着警报器。