velocity

Short definition from Wiktionary

Noun

1. 1
   A vector quantity that denotes the rate of change of position with respect to time, combining speed with a directional component.
2. 2
   Rapidity of motion.
3. 3
   The rate of occurrence.
4. 4
   The number of times that an average unit of currency is spent during a specific period of time.
5. 5
   The value corresponding to how hard a key is struck on a MIDI controller or keyboard.