reporting verb
1- say something in a low or barely audible voice, especially in dissatisfaction or irritation（尤指不满、愤怒时）小声地说; 嘟哝; 咕哝：
with obj. he muttered something under his breath他压低嗓子嘀咕着什么
with direct speech 'I knew she was a troublemaker,' Rebecca muttered“我知道她就会惹是生非”, 丽贝卡嘟哝着
no obj. she muttered in annoyance as the keys slid from her fingers.钥匙从她手里滑了下来, 她随即烦躁地嘟哝了一声。
1.1
- no obj. speak privately or unofficially about someone or something; spread rumours私下谈论; 散布流言：
back-benchers were muttering about the next reshuffle.
后座议员们私下议论着下一次的内阁改组。
- a barely audible utterance, especially a dissatisfied or irritated one小声说出的话（尤指怨言）：
a little mutter of disgust.
表示厌恶的小声抱怨。
派生词
mutterer
nounmutteringly
adverb词源
late Middle English: imitative; compare with German dialect muttern.