Supersonic is a term used to describe things which fly faster than the speed of sound. At 70 degrees Fahrenheit (21 Celsius), for an object to fly faster than sound, it must travel 761 miles per hour (1224.71 kilometers per hour).
American P-47 Thunderbolts in World War II came close to supersonic speeds in a dive, but the first person to break the sound barrier in level flight was American Air Force pilot "Chuck" Yeager in the X-1 experimental aircraft.