1. [n]  reckless or malicious behavior that causes discomfort or annoyance in others
2. [n]  the quality or nature of being harmful or evil

MISCHIEF is a 8 letter word that starts with M.

1. \Mis"chief\, n. [OE. meschef bad result, OF. meschief;
   pref. mes- (L. minus less) + chief end, head, F. chef chief.
   See {Minus}, and {Chief}.]
   1. Harm; damage; esp., disarrangement of order; trouble or
      vexation caused by human agency or by some living being,
      intentionally or not; often, calamity, mishap; trivial
      evil caused by thoughtlessness, or in sport. --Chaucer.
   
            Thy tongue deviseth mischiefs.        --Ps. lii. 2.
   
            The practice whereof shall, I hope, secure me from
            many mischiefs.                       --Fuller.
   
   2. Cause of trouble or vexation; trouble. --Milton.
   
            The mischief was, these allies would never allow
            that the common enemy was subdued.    --Swift.
   
   {To be in mischief}, to be doing harm or causing annoyance.
   
   
   {To make mischief}, to do mischief, especially by exciting
      quarrels.
   
   {To play the mischief}, to cause great harm; to throw into
      confusion. [Colloq.]
   
   Syn: Damage; harm; hurt; injury; detriment; evil; ill.
   
   Usage: {Mischief}, {Damage}, {Harm}. Damage is an injury
          which diminishes the value of a thing; harm is an
          injury which causes trouble or inconvenience; mischief
          is an injury which disturbs the order and consistency
          of things. We often suffer damage or harm from
          accident, but mischief always springs from perversity
          or folly.
   
   

2. \Mis"chief\, v. t.
   To do harm to. [Obs.] --Milton.