Webster's Revised Unabridged Dictionary · 1913

Mump

Mump , intransitive verb

[Akin to mumble; compare Dutch mompen to cheat; perh. orig., to whine like a beggar, Dutch mompelen to mumble. See Mumble, Mum, and compare Mumps.]

1.
To move the lips with the mouth closed; to mumble, as in sulkiness.
He mumps, and lovers, and hangs the lip. — Taylor, 1630
2.
To talk imperfectly, brokenly, or feebly; to chatter unintelligibly.
3.
To cheat; to deceive; to play the beggar.
And then when mumping with a sore leg,... canting and whining. — Burke
4.
To be sullen or sulky. [Provincial English]

Mump , transitive verb

1.
To utter imperfectly, brokenly, or feebly.
Old men who mump their passion. — Goldsmith
2.
To work over with the mouth; to mumble; as, to mump food.
3.
To deprive of (something) by cheating; to impose upon.