Meaning:

“洗” means to “wash,” and “白” means “white.” Similar to the English word “whitewash,” this term is often used by Chinese netizens to refer to the situation where a character originally believed to be evil in an animation, movie, TV show or novel turns out to be on the good side. It’s also used as a verb to mean “having one’s bad reputation absolved.”

Example:

A: 那个出轨的男明星好像比之前更火了，所以，他现在算是成功洗白了吗？

Nàgè chūguǐ de nán míngxīng hǎoxiàng bǐ zhīqián gèng huǒ le，suǒyǐ，tā xiànzài suàn shì chénggōng xǐbái le ma？

That movie star who had an extramarital affair seems to be even more popular than before. Has he succeeded in having his bad reputation absolved?

B: 网络时代大家的注意力集中时间很短，大家都已经淡忘这件事。

Wǎngluò shídài dàjiā de zhùyìlì jízhōng shíjiān hěn duǎn，dàjiā dōu yǐjīng dànwàng zhèjiàn shì。

People have a very short attention span in this Internet era. I guess no one still remembers his affair.