The term 'run quickly' can be expressed in four different ways, each with six letters. The first is 'SPRINT, ' which is a type of running that involves short bursts of speed and is often used in competitive sports. The second is 'DASH, ' which is a short, fast run that is usually done over a short distance. The third is 'HARE, ' which is a type of mammal that is known for its ability to run quickly. Finally, the fourth is 'SCUD, ' which is a type of running that involves quick, light steps. All of these terms can be used to describe running quickly.