To remove dirt or stains by washing. She tried to wash out the coffee stain from her shirt.
To be removed or disappear as a result of washing. The color of the fabric will wash out after a few washes.
To erode or be eroded by water. The heavy rain caused the road to wash out.
To cancel or nullify an event or activity due to rain or other adverse conditions. The baseball game was washed out due to the storm.