undertoneWiktionary 原文中文来自 ECDICTn.低音，浅色，小声构词拆分under-前缀Beneath, under · (figurative) To go from one side to the other; to progress along a path+tone词根/词干词源说明From under- + tone.释义（英文）名词 NounAn auditory tone of low pitch or volume.(figurative) An implicit message perceived subtly alongside, but not detracting noticeably from, the explicit message conveyed in or by a book, film, speech or similar (contrast with overtone); an undercurrent