late 14c., mochenes, "largeness of size" (a sense now obsolete); c. 1400, "greatness of number or degree; state of being great in quantity or extent," from much + -ness. Earlier was Middle English muchelnesse (c. 1200). Phrase much of a muchness "of about the same importance or value" is attested from 1728.
Ms.
MSG
Mstislav
much
muchly
muchness
mucilage
mucilaginous
muck
muck-a-muck
muckluck