Whitewash is a mixture of lime or chalk and water that is used for painting walls white.

If a wall or building has been whitewashed, it has been painted white with whitewash.

If you say that people whitewash something, you are accusing them of hiding the unpleasant facts or truth about it in order to make it acceptable.

Whitewash is an attempt to hide the unpleasant facts or truth about someone or something.

In sports, if a player or team whitewashes an opponent, they win very easily, and their opponent does not get any points at all.