siren

Everyday

1. A device that makes a loud wailing or rising-and-falling sound to warn people, used on ambulances, fire engines and police cars, and for warnings about danger. tree →
2. In Greek myths, the Sirens were creatures whose beautiful singing lured sailors onto rocks. tree →

In the lessons

In road safety, when you hear a siren, look around: an emergency vehicle is coming; stay on the pavement and let it pass. Drivers pull over to let it through. Some places have sirens to warn of floods, storms, tornadoes or fires; at school, a siren or alarm means follow the drill. In science, the Doppler effect is why a siren sounds higher as it comes towards you and lower as it goes away. In stories, a siren is a dangerous, tempting singer. Phrases: "hear a siren", "sirens wailing", "a police siren", "tornado siren", "air-raid siren".

Examples

• We heard a siren and the ambulance raced past. tree →
• When you hear a siren, stay on the pavement. tree →
• Cars pulled over for the fire engine with its siren on. tree →
• The tornado siren sounded across the town. tree →
• The siren got lower in pitch as the police car drove away. tree →
• In the myth, the Sirens sang to the sailors. tree →
• The siren woke the baby. tree →
• At night we could hear sirens in the city. tree →

Note

Countable: a siren, sirens. Spelling: s-i-r-e-n. Emergency numbers: 911 (USA, Canada), 999 (UK, Ireland also 112), 000 (Australia), 111 (New Zealand). A siren is a warning, so take it seriously.