Sonic means relating to sound or sound waves. When a jet flies faster than the speed of sound, it creates a sonic boom, a thunderous crack that rattles windows and startles people on the ground. The boom happens because the jet pushes through air faster than sound waves can move, creating a powerful shock wave.

Scientists use the word sonic when studying how sound behaves. Sonic sensors can measure distances by bouncing sound waves off objects, similar to how bats navigate in the dark. Ultrasonic cleaning machines use sound waves at frequencies too high for humans to hear to shake dirt loose from jewelry or medical instruments.

You might encounter sonic in unexpected places: sonic toothbrushes vibrate rapidly to clean teeth, and some restaurants have sonic ice machines that make small, chewable ice nuggets.

When something moves at supersonic speed, it travels faster than sound. When something is subsonic, it moves slower than sound. A regular airplane is subsonic, while a military fighter jet can go supersonic. Concorde, a passenger jet that flew from 1969 to 2003, could cross the Atlantic Ocean at supersonic speeds.