Source : Webster's Revised Unabridged Dictionary (1913)

Mump \Mump\, v. i. [Akin to mumble; cf. D. mompen to cheat;
   perh. orig., to whine like a beggar, D. mompelen to mumble.
   See {Mumble}, {Mum}, and cf. {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. [Prov. Eng.]

Mump \Mump\, v. t. [imp. & p. p. {Mumped}; p. pr. & vb. n.
   {Mumping}.]
   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.