Definition of "cannonball" [cannonball]

• A round projectile fired from a cannon. (noun)
• A jump into water made with the arms grasping the upraised knees. (noun)
• Something, such as a fast train, moving with great speed. (noun)
• Sports A fast low serve in tennis. (noun)
• To travel with great speed. (verb-intransitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "A few steps away, a kneeling artilleryman lifts one cannonball from a pile, presumably to bring it to the cannoneers for loading."
• "This cosmic cannonball is challenging theories to explain its blistering speed."
• "In our high school class there are only fifteen boys, and every summer some of us camp out by the river and cannonball from the cliffs into the current."