velocity

noun

Etymology: From Middle French vélocité, from Latin vēlōcitās (“speed”), from vēlōx (“fast”), thus a doublet of veloce.

1. A vector quantity that denotes the rate of change of position with respect to time, combining speed with a directional component.

   “A car racing in a circle may retain the same speed while continually changing its velocity.”

   “Usually, however, confluence is associated with an increase in air velocity and diffluence with a decrease. In the intermediate case, confluence is balanced by an increase in wind velocity and diffluence by a decrease in velocity.”

2. A rapidity of motion.

   “The train was travelling at a slower velocity than usual.”

   “Over the winter-solid Roads, goes a great seething,— of mounted younger Gentlemen riding together by the dozens upon rented horses, Express Messengers in love with pure Velocity, Disgruntl'd Suitors with Pistols stuff'd in their Spatterdashes, seal'd Waggons not even a western Black-Boy would think of detaining.”

3. The rate of occurrence.
4. The number of times that an average unit of currency is spent during a specific period of time.
5. The value corresponding to how hard a key is struck on a MIDI controller or keyboard.