1. [n]  open rebellion against constituted authority (especially by seamen or soldiers against their officers)
2. [v]  engage in a mutiny against an authority

MUTINY is a 6 letter word that starts with M.

1. \Mu"ti*ny\, n.; pl. {Mutinies}. [From mutine to mutiny,
   fr. F. se mutiner, fr. F. mutin stubborn, mutinous, fr. OF.
   meute riot, LL. movita, fr. movitus, for L. motus, p. p. of
   movere to move. See {Move}.]
   1. Insurrection against constituted authority, particularly
      military or naval authority; concerted revolt against the
      rules of discipline or the lawful commands of a superior
      officer; hence, generally, forcible resistance to rightful
      authority; insubordination.
   
            In every mutiny against the discipline of the
            college, he was the ringleader.       --Macaulay.
   
   2. Violent commotion; tumult; strife. [Obs.]
   
            o raise a mutiny betwixt yourselves.  --Shak.
   
   {Mutiny act} (Law), an English statute re["e]nacted annually
      to punish mutiny and desertion. --Wharton.
   
   Syn: See {Insurrection}.
   
   

2. \Mu"ti*ny\, v. i. [imp. & p. p. {Mutinied}; p. pr. & vb.
   n. {Mutinying}.]
   1. To rise against, or refuse to obey, lawful authority in
      military or naval service; to excite, or to be guilty of,
      mutiny or mutinous conduct; to revolt against one's
      superior officer, or any rightful authority.
   
   2. To fall into strife; to quarrel. [Obs.] --Shak.