Webster's Revised Unabridged Dictionary · 1913

Mumble

Mumble , transitive verb

[Old English momelen; compare Dutch mompelen, mommelen, German mummelen, Swedish mumla, Danish mumle. Compare Mum, a., Mumm, Mump, v.]

1.
To speak with the lips partly closed, so as to render the sounds inarticulate and imperfect; to utter words in a grumbling indistinct manner, indicating discontent or displeasure; to mutter.
Peace, you mumbling fool. — Shakespeare
A wrinkled hag, with age grown double, Picking dry sticks, and mumbling to herself. — Otway
2.
To chew something gently with closed lips.

Mumble (mum"b'l) , transitive verb

1.
To utter with a low, inarticulate voice. — Bp. Hall
2.
To chew or bite gently, as one without teeth.
Gums unarmed, to mumble meat in vain. — Dryden
3.
To suppress, or utter imperfectly.