HSK 7-9
瞒
mán动
to conceal from; to keep (sb) in the dark
他一直瞒着家人独自治疗。
Tā yìzhí mán zhe jiārén dúzì zhìliáo.
He kept his treatment secret from his family.
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Appears across levels (7-9) in the HSK 3.0 word list.