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hy·dro·qui·none -kwin-'ōn, -'kwin-.ōn n a bleaching agent C6H6O2 used topically to remove pigmentation from hyperpigmented areas of skin (as a lentigo or freckle)
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hy·dro·quin·one (hi″dro-kwĭ-nōnґ) [USP] the reduced form of quinone, containing two hydroxyl groups; applied topically to bleach hyperpigmented skin.Medical dictionary. 2011.