"Speed" can be either a noun or verb: Please see the related link below:
It is called a definition.
The definition of the speed of light in a vacuum is 300,000,000 meters/sec, or 186,000 miles/sec.
Initial speed is the original, beginning speed of an object.
Quickness, speed
they are fast
"instantaneous speed"
Great speed is faster than normal.
The speed that an object moves through the air.
By definition acceleration is the change in velocity (speed).
The definition of haste is: swiftness of motion; speed; celerity or unnecessarily quick action; thoughtless, rash, or undue speed
How fast you are
There are different types of speed formulas: Speed= Wavelength(frequency) or Speed= Distance/Time