/'mʌtə(r); `mʌtɚ/ v
1 [I, Ipr, Tn, Tn.pr, Tf, Dn.pr] ~ (sth) (to sb) (about sth) speak or say (sth) in a low voice that is hard to hear 低语; 咕哝（某事）
*Don't mutter! I can't hear you. 别叽叽咕咕的! 我听不见.
* Sarah was muttering away to herself as she did the washing-up. 萨拉一边洗碗碟一边独自咕哝个没完.
* He muttered something (to the salesgirl) (about losing his wallet). 他低声（向女售货员）述说着（他的钱包丢了）.
2 [I, Ipr] ~ (about/against/at sb/sth) complain or grumble privately or in a way that is not openly expressed （私下）埋怨, 发牢骚, 讲怪话
*For some time people had been muttering about the way she ran the department. 人们对她的管理方式私下抱怨已有时日.
3 [I] (of thunder) be heard distantly; rumble （指雷）自远处发低沉声, 隆隆作响.

n (usu sing 通常作单数) indistinct utterance or sound 含糊低语声; 含混不清的声音.

v
[Date: 1300-1400; Origin: Probably from the sound]
[I and T]
to speak in a low voice, especially because you are annoyed about something, or you do not want people to hear you
mutter to yourself
　'I never want to come here again,' he muttered to himself.
　Elsie muttered something I couldn't catch and walked off.
　'He's such an unpleasant man,' Alyssia muttered under her breath .
mutter about
　What are you two muttering about?
[I]
to complain about something or express doubts about it, but without saying clearly and openly what you think
mutter about
　Some senators muttered darkly about the threat to national security.
>muttern [singular]
　His voice subsided to a mutter.
>mutteringn [U and C]
　The mutterings about his leadership continued to grow.