1. phrasal verbIf you wash out a container, you wash the inside of it.
It was my job to wash out the fish tank. [VERB PARTICLE noun]
2. phrasal verbIf dye or dirt washes out, it can be removed by washing.
With permanent tints, the result won't wash out. [VERB PARTICLE]
3. phrasal verbIf rain washes out a sports game or other event, it spoils it or prevents it from continuing.
Rain washed out five of the last seven games. [VERB PARTICLE noun]
4. See also washed-out, washout
See full dictionary entry for wash