What word means to sing quietly?

There are a few words that could describe singing quietly, depending on the specific nuance you want to convey:

* Hum: This implies a low, quiet, and often unarticulated singing sound.

* Murmur: This suggests a soft, low, and often indistinct singing sound.

* Whisper: This implies a very quiet, almost inaudible singing sound.

* Croon: This describes a soft, low, and often melodious singing sound.

* Softly: This is a general term that can be used to describe any kind of quiet singing.

* Subdued: This suggests a restrained and quiet singing style.

The best word to use will depend on the context and the specific type of quiet singing you are describing.