cannonball

noun

1. A spherical projectile fired from a smoothbore cannon.
2. An explosive-filled hollow iron sphere fused through a hole and intended to explode at a calculated distance rather than explode on impact.
3. The act of jumping (typically into a swimming pool) with the legs bent and the arms wrapped around the knees to create a large splash, mimicking the flight and shape of a cannonball.

   “The New Yorker, 30 August 2004, p.40”

   “The cannonball could be called the S.U.V. of the pool — oversized, brash, hormonally hardwired.”

4. (figuratively, slang)Something that moves fast, especially a fast train.

   “Meetings of the model train club always begin with the song "Wabash Cannonball".”

5. A served ball that travels with great speed and describes little or no arc in flight.

verb

1. (intransitive)To jump or dive into water, performing a cannonball landing.

   “He cannonballed into the pool, drenching us all.”

2. (intransitive)To career; to move rapidly.

   “The car cannonballed past.”