Definition of "ballista" [bal•lis•ta]

• An ancient and medieval engine of warfare used to hurl heavy projectiles at a target. (noun)

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.

• "From that shelter they suddenly appeared and began the attack, so that the guards were neither able to use the engine called the ballista (for these engines do not send their missiles except straight out), nor, indeed, could they ward off their assailants with their arrows, since the situation was against them on account of the large shields."
• "There was also a great deal of work on the ballista which is a hop forward with a loud slap of the foot."
• "The fun ended when the ballista I'd constructed using binder clips, rubber bands and the side of a filing cabinet drawer launched a projectile over my intended target and smack into a Judge's back."