Etymology: Low German mummenschanze throw in a dice game played by masked revelers, from Middle Low German, from mummen dice game played by masked revelers (from mummen to go masked, perhaps from Middle French momer) + (assumed) Middle Low German schanze throw of dice, from Middle French chance throw of dice, chance — more at chance
1. : an old dice game in which the caster is not permitted to choose the player with whom he contests the stake — compare hazard
II. intransitive verb
1. : masquerade
2. chiefly dialect : to be silent out of caution or stupidity
III. adjective
chiefly dialect : silent
IV. adverb
Etymology: mumchance (III)
chiefly Britain : silently
peering down mumchance at its reflection in the river — Richard Llewellyn
Useful english dictionary. 2012.