undertone

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An underlying or implied tendency or meaning; an undercurrent.
2. n. A tone of low pitch or volume, especially of spoken sound.
3. n. A pale or subdued color.
4. n. A color applied under or seen through another color.

Century Dictionary and Cyclopedia

1. n. In musical acoustics: Same as combinational tone (which see, under tone), One of a series of tones reckoned downward from a given tone in exactly the same way that the series of overtones or harmonics is reckoned upward. The interval from the given tone to the first undertone is an octave; to the second, an octave and a fifth; to the third, two octaves, etc. (See cut.) While this series is not actually heard in any case, yet it is claimed by many theorists recently that the relations involved are sufficiently felt to explain the minor mode as in a true sense an inversion or polar opposite of the major. Hence has arisen a large number of terms beginning with under-, denoting intervals and chords regarded downward corresponding with the usual names of intervals and chords regarded upward. See cut under harmonic, n., 1.
2. n. A low or subdued tone; a tone less forcible than is usual, as in speaking: as, to say something in an undertone.
3. n. A state or degree of tone, as of the physical or mental faculties, below their usual condition. The color of a pigment when seen in very thin layers on a white or light-colored surface. Also— A low, subdued color: as, gray undertones.

Wiktionary

1. n. an auditory tone of low pitch or volume
2. n. an implied meaning; an undercurrent
3. n. a pale colour, or one seen underneath another colour

GNU Webster's 1913

1. n. A low or subdued tone or utterance; a tone less loud than usual.

WordNet 3.0

1. n. a quiet or hushed tone of voice
2. n. a pale or subdued color
3. n. a subdued emotional quality underlying an utterance; implicit meaning