D defs.my
Entry 1 sense Webster, 1913

Undertone

/ŭn'-dẽrt-ōnˌ/ · Un·der·tone · IPA /ˈʌndə(ɹ)təʊn/
01 n. A low or subdued tone or utterance; a tone less loud than usual.
  1. 1.
    A low or subdued tone or utterance; a tone less loud than usual.