The Collaborative International Dictionary
Whitewash \White"wash`\, v. t. [imp. & p. p. Whitewashed; p. pr. & vb. n. Whitewashing.]
To apply a white liquid composition to; to whiten with whitewash.
To make white; to give a fair external appearance to; to clear from imputations or disgrace; hence, to clear (a bankrupt) from obligation to pay debts.
In various games, to defeat (an opponent) so that he fails to score, or to reach a certain point in the game; to skunk. [Colloq., U. S.]
to gloss over or cover up (crimes or misfeasance).
Wiktionary
n. 1 The application of whitewash. 2 (context figuratively English) The effacement of errors or bad actions. vb. (present participle of whitewash English)
Wikipedia
To whitewash is a metaphor meaning "to gloss over or cover up vices, crimes or scandals or to exonerate by means of a perfunctory investigation or through biased presentation of data". It is especially used in the context of corporations, governments or other organizations.
Usage examples of "whitewashing".
And in still another panic of fright we have this same tough civilisation saving its honour by condemning an innocent man to multiform death, and hugging and whitewashing the guilty one.
Cold War, he cooperated with the Soviets at the Nuremberg Trials, whitewashing their joint aggression with Hitler under the Nazi-Soviet Pact.