undertone

[ uhn-der-tohn ]

/ ˈʌn dərˌtoʊn /

a low or subdued tone: to speak in undertones.

an unobtrusive or background sound: an undertone of static from the receiver.

an underlying quality or element; undercurrent: There was an undertone of regret in his refusal.

a subdued color; a color modified by an underlying color.

Origin of undertone

First recorded in 1800–10; under- + tone

I heard then a sigh next to me that had an undertone not unlike a snarl.

Remembering Nora Ephron as Our Dorothy Parker, but More |Stephen Schiff |June 27, 2012 |DAILY BEAST
The undertone riffs off the “un-American” implications of the 2008 campaign directed at then-Sen.

They Still Think He's Muslim |John Avlon |June 12, 2009 |DAILY BEAST
That,” she told her husband, in an undertone, “is a picture of the officer I saw on the lawn.

Adventurings in the Psychical |H. Addington Bruce
And yet there was an undertone in his expression which I could not define.

The Homicidal Diary |Earl Peirce

He walked abruptly out to where some of his men were standing by their horses, and he said something in an undertone.

The Coyote |James Roberts
"But I can't," she was heard to murmur in an undertone to the disappointed Bruce.

Harriet and the Piper |Kathleen Norris
Now it was resonant and strong, though still only an undertone.

The Blind Spot |Austin Hall

undertone

/ (ˈʌndəˌtəʊn) /

a quiet or hushed tone of voice

an underlying tone or suggestion in words or actions his offer has undertones of dishonesty

a pale or subdued colour