Here's a breakdown:
* Tumbledown: Means to fall down or collapse, emphasizing the downward motion.
* Touchdown: In sports, it refers to the act of touching the ground with the ball, again highlighting the downward action.
* Downspout: A pipe that carries water down from a roof, with "down" directly indicating the direction of water flow.
While each word has its own specific meaning, they all share the common element of "down," signifying a downward direction or movement.