Mud Lark.  A fellow who goes about by the water side
  picking up coals, nails, or other articles in the mud.  Also
  a duck.

Muff.  The private parts of a woman.  To the well wearing
  of your muff, mort; to the happy consummation of
  your marriage, girl; a health.

Muffling cheat.  A napkin.

MUGGLETONIANS.  The sect or disciples of Lodowick
  Muggleton.

MULLIGRUBS.  Sick of the mulligrubs with eating chopped
  hay:  low-spirited, having an imaginary sickness.

Mum.  An interjection directing silence.  Mum for that; I
  shall be silent as to that.  As mute as Mumchance, who
  was hanged for saying nothing; a friendly reproach to any
  one who seems low-spirited and silent.

Mumchance.  An ancient game like hazard, played with
  dice:  probably so named from the silence observed in playing
  at it.

Mum glass.  The monument erected on Fish-street Hill,
  London, in memory of the great fire in 1666.

Mumble A sparrow.  A cruel sport practised at wakes
  and fairs, in the following manner:  A cock sparrow
  whose wings are clipped, is put into the crown of a hat; a
  man having his arms tied behind him, attempts to bite off
  the sparrow’s head, but is generally obliged to desist, by
  the many pecks and pinches he receives from the enraged
  bird.

Mummer.  The mouth.

MUMPERS.  Originally beggars of the genteel kind, but
  since used for beggars in general.

MUMPERS hall.  An alehouse where beggars are harboured.

MUNDUNGUS.  Bad or rank tobacco:  from mondongo, a
  Spanish word signifying tripes, or the uncleaned entrails
  of a beast, full of filth.

Mung.  To beg.

Muns.  The face, or rather the mouth:  from the German
  word Mund, the mouth.  Toute his muns; look at his face.

Munster plums. Potatoes.  Irish.

Munster heifer.  An Irish woman.  A woman with
  thick legs is said to be like a Munster heifer; i.e. beef to
  the heels.

Murder.  He looked like God’s revenge against murder;
  he looked angrily.

MURPHIES.  Potatoes.

Mushroom.  A person or family suddenly raised to riches
  and eminence:  an allusion to that fungus, which starts up
  in a night.

Music.  The watch-word among highwaymen, signifying
  the person is a friend, and must pass unmolested.  Music
  is also an Irish term, in tossing up, to express the harp side,
  or reverse, of a farthing or halfpenny, opposed to the head.

Mute.  An undertaker’s servant, who stands at the door of
  a person lying in state:  so named from being supposed
  mute with grief.