smoke alarm
nounUK /ˈsməʊk əˌlɑːm/
US /ˈsmoʊk əˌlɑːrm/
A small device that makes a loud noise when it smells smoke.
The smoke alarm beeped loudly when the toast burned.
OTHER MEANINGS
2. A warning device that senses smoke and sounds an alert to prevent fire danger.
Every bedroom should have a working smoke alarm.
3. A household safety gadget often tested monthly by pressing its button.
Dad tested the smoke alarm before we went on holiday.
4. An electronic sensor that can be powered by batteries or household electricity.
The smoke alarm started chirping because its battery was low.