siren noun

ADJ. approaching The cars had stopped at the sound of the approaching siren. | air-raid, ambulance, factory, police, warning

VERB + SIREN put on, sound, switch on The ships all sounded their sirens. | hear

SIREN + VERB go (off), sound, start | blare, howl, scream, wail The ambulance sped off with its siren wailing. | die away The police siren died away into the hot night.