A slang term, popular amongst US troops like myself, referring to Iraqi or Afghani insurgents. Derived from the overused Arabic word, mujahideen, which means "one or a group of holy fighter(s)." Insurgents refer to themselves as a mujahideen, when really they are just a bunch of fucking terrorists.
The muj in Fallujah ran down the street, spraying their AK's with no accuracy, and got blown to haji jerkey by us. HOOAH!