The word "washout" can have a few different meanings, and I’ll explain them all clearly.
In a general sense: A "washout" can refer to something that is unsuccessful or fails completely. For example, if someone tries to start a project and it doesn’t work out at all, you could say it was a washout.
In nature: A "washout" can also refer to the process of water washing away soil or gravel. This often happens after heavy rain or storms when the ground is eroded, creating a gap or a hole.
"Washout" can refer to both an unsuccessful event or the physical process of erosion.