Weak

 is a target priority, and exclusive to the BTD4 Generation. It is the fourth target priority of the majority of the towers in the game. Towers set on the Weak target priority will target the weakest bloon visible within its visible range.

The target priority Weak was replaced by Close starting from Bloons TD 5 Flash, and has continued since the rest of the Bloons TD 5 Generation began to expand to other games.