verb · to apply black substance to a surface, such as a face for camouflage

特种兵在执行夜间任务前把脸抹黑。

verb · to obliterate or cover up text or images, often for censorship

公文中的敏感信息被用墨水抹黑了。

verb · to discredit, defame, smear someone's reputation, or bring shame upon oneself or others

他故意在网上散布谣言来抹黑对手。