Here are some nuances of the word:
* Low volume: Muttering is typically very quiet, almost a whisper.
* Indistinct: It can be difficult to understand what is being said.
* Hesitation: Muttering can indicate someone is unsure of what they're saying or feeling hesitant to speak.
* Anger or frustration: Muttering can also be a sign of anger or frustration, especially if the words are spoken in a harsh or growling tone.
* Secret or concealed: Muttering can be used to convey something in a private or hidden way.
Examples:
* "He muttered something about needing to leave early."
* "The old man muttered to himself as he shuffled down the street."
* "She muttered a curse under her breath."
It's important to note: While muttering is often associated with negative emotions, it can also be used in a neutral or even positive way, depending on the context.