ultra-quiet
adjective (also ultraquiet) uk/ˌʌl.trəˈkwaɪ.ət/ us/ˌʌl.trəˈkwaɪ.ət/
极度安静
extremely quiet; making very little or no sound
The fan has an ultraquiet motor so that you hardly notice it is running. 风扇有一个超静音电机，因此您几乎不会注意到它在运转。
The navy uses sonar to detect ultra-quiet submarines that might be lurking in nearby waters.
- More examples
- The hiking trail is located in an ultra-quiet, densely wooded area with views of ravines and streams.
- Public transport is provided by a fleet of ultra-quiet electric buses that travel throughout the city.
- The tiny hovering object in the sky turned out to be an ultraquiet surveillance drone.