#speed__velocity  distance travelled per unit time
  supertype:  #rate  a magnitude or frequency relative to a time unit; "they traveled at a rate of 55 miles per hour"; "the rate of change was faster than expected"
  subtype:  #airspeed  the speed of an aircraft relative to the air in which it is flying
  subtype:  #escape_velocity  the minimum velocity needed to escape a gravitational field
  subtype:  #groundspeed  the speed of an aircraft relative to the ground
  subtype:  #hypervelocity  excessive velocity; "the meteorites struck the earth with hypervelocity impacts"
  subtype:  #muzzle_velocity  the velocity of a projectile as it leaves the muzzle of a gun
  subtype:  #speed_of_light__light_speed__lightspeed__c  the speed at which light travels in a vacuum; the constancy and universality of the speed of light is recognized by defining it to be exactly 299,792,458 meters per second
  subtype:  #steerageway  (nautical) the minimum rate of motion needed for a vessel to be maneuvered
  subtype:  #terminal_velocity  the constant maximum velocity reached by a body falling through the atmosphere under the attraction of gravity

No statement uses or specializes #speed; click here to add one.