undertone

noun

1. a low or subdued tone: to speak in undertones.
2. an unobtrusive or background sound: an undertone of static from the receiver.
3. an underlying quality or element; undercurrent: There was an undertone of regret in his refusal.
4. a subdued color; a color modified by an underlying color.

noun

1. a quiet or hushed tone of voice
2. an underlying tone or suggestion in words or actionshis offer has undertones of dishonesty
3. a pale or subdued colour

n.1762, “low or subdued tone,” from under + tone. Figurative sense of “undercurrent of feelings, etc.,” is attested from 1861.