Definitions
1.nounAn auditory tone of low pitch or volume.
2.nounAn implicit message perceived subtly alongside, but not detracting noticeably from, the explicit message conveyed in or by a book, film, verbal dialogue or similar (contrast with overtone); an undercurrent.
3.nounA pale colour, or one seen underneath another colour.
4.nounA low state of the physical faculties.
5.verbTo accompany as an undertone.
6.verbTo say or speak in an undertone.
7.verbTo present as less important, noticeable or prominent.