Meaning 100%, complete, or to the fullest extent; literally 'without discount or reduction'.
折、扣出售商品时，按定价减去的成数。没有折扣，表示完全、十足的意思。
老舍《女店员》第二幕如今的妇女跟男人不折不扣一样尊贵！”
He is a 100% honest person, truly reliable.
Learn the next connected idiom: 不折不扣 (bù zhé bù kòu) → 扣人心弦 (kòu rén xīn xián)
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