undertone

1. N-COUNT If you say something in an undertone, you say it very quietly. 低聲['in' N]

"What d'you think?" she asked in an undertone. “你覺得呢？”她低聲問。

2. N-COUNT If something has undertones of a particular kind, it suggests ideas or attitudes of this kind without expressing them directly. 隱含意[with supp]

...a witty, racy story with surprisingly serious undertones. ...一個(gè)詼諧活潑卻有十分嚴(yán)肅的隱含意的故事。