[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）. 
[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. 
[I] (of thunder) be heard distantly; rumble （指雷）自远处发低沉声, 隆隆作响.> mutter n (usu sing 通常作单数) indistinct utterance or sound 含糊低语声; 含混不清的声音.
mutterer / 5mQtErE(r); `mQtLrL/ n person who mutters 喃喃低语者.
muttering / 5mQtErIN; `mQtErIN/ n [U] (also mutterings[pl]) complaints that are privately or not openly expressed 私下的抱怨.