'Mumm' definitions:

Definition of 'Mumm'

From: GCIDE

Mumm \Mumm\, v. i. [imp. & p. p. Mummed; p. pr. & vb. n. Mumming.] [D. mimmen to mask, mom a mask; akin to G. mumme disguise; prob. of imitative origin, and akin to E. mum, mumble, in allusion to the indistinctness of speech occasioned by talking from behind a mask. Cf. Mumble, Mummery.] To sport or make diversion in a mask or disguise; to mask. [1913 Webster]
With mumming and with masking all around. --Spenser. [1913 Webster]