What does "mutter" mean?

Mutter: Meantime your filthy foreigner will stare, And mutter to himself. Dryden.

Additional senses

  1. 2.To sound with a low, rumbling noise. Thick lightings flash, the muttering thunder rolls. Pope.
  2. 3.To utter with imperfect articulations, or with a low voice; as, to mutter threats. Shak.
  3. 4.Repressing or obscure utterance.

Sources