| Noun | 1. | ballistic pendulum - a physical pendulum consisting of a large mass suspended from a rod; when it is struck by a projectile its displacement is used to measure the projectile's velocity gun pendulum - a ballistic pendulum consisting of a suspended gun; the velocity of a projectile in the bore of a gun can be measured by the recoil when the gun is discharged compound pendulum, physical pendulum - pendulum consisting of an actual object allowed to rotate freely around a horizontal axis |