Definitions of speed:

• noun:   changing location rapidly
• noun:   a rate (usually rapid) at which something happens

  Example: "The project advanced with gratifying speed"

• noun:   distance travelled per unit time
• noun:   a central nervous system stimulant that increases energy and decreases appetite; used to treat narcolepsy and some forms of depression
• noun:   the ratio of the focal length to the diameter of a (camera) lens system
• verb:   travel at an excessive or illegal velocity

  Example: "I got a ticket for speeding"

• verb:   move very fast

  Example: "The runner zipped past us at breakneck speed"

• verb:   cause to move faster
• verb:   move faster
• verb:   step on it
• name:  A surname (rare: 1 in 33333 families; popularity rank in the U.S.: #4015)