The story
By analogy with money laundering.
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: The act of legitimizing misinformation by presenting it in the same manner as widely trusted news sources, in order to increase its exposure and lend it credibility with the target audience; in some cases, the process may be repeated several times, through increasingly trusted sources. Full definition →
By analogy with money laundering.
Etymology from Wiktionary, CC BY-SA 4.0.