Bounce is an attack behavior characterized be a projectile changing trajectory after hitting a wall. It was introduced in BTD6 with the Juggernaut upgrade, which was later added to the Spike-o-pult upgrade in in Version 12.0 as well. It is part of the damage types family.
Bounce is represented on the Bloons Wiki as 
, the upgrade icon for Ultra-Juggernaut upgrade, as this is the most powerful upgrade of it's attack behavior.
Any attack must change its trajectory after hitting a wall to be considered Bounce . Because of this, only Sentry Expert with its Crushing Sentries and Apex Plasma Master, are the only other instances of Bounce being utilized. It is distinct from Contact Damage 
because the projectile needs to hit a wall or an obstacle in order to gain the ability to hit the same bloon again.
All attacks require an upgrade to have bounce.
There is an another type of Bounce, called Side Bounce (or Edge Bounce) which pertains to BSM2 (Mobile), BATTD, and Bloons Pop! where Spikey Chaos' spiked balls (and any projectile with Bouncy Shots), Wizard Lord's projectiles, and monkeys/projectiles bounce on the sides of the screen. It is represented on Bloons Wiki as 
, the BATTD portrait for Wizard Lord, as he is famous for firing bolts that bounce around the entire play area.
