An undertone refers to a quiet, subdued, or hushed tone of voice used when speaking softly or in a restrained manner.
It can describe an implicit or underlying meaning — a subtle suggestion or emotional nuance present in words, actions, or behavior that is not stated outright.
“Her friendly words carried an undertone of warning.”
In visual contexts, undertone means a pale, muted, or subdued color that lies beneath the surface hue, influencing the overall appearance.
Author’s summary: The word undertone expresses softness, subtlety, or underlying nuance — whether in voice, intent, or color tone.