engine engine /ˈɪndʒən/

noun

1. () Motor that converts thermal energy to mechanical work  ( engine )
   motor that converts thermal energy to mechanical work
    The engine of my motorbike needs to be tuned up
   The engine of my motorbike needs to be tuned up
   
   
2. () Something used to achieve a purpose  ( engine )
   something used to achieve a purpose
    An engine of change
   an engine of change
   
3. () A wheeled vehicle consisting of a self-propelled engine that is used to draw trains along railway tracks  ( locomotive , locomotive engine , railway locomotive [Canadian, British] , engine , railroad locomotive [ N. American] )
   a wheeled vehicle consisting of a self-propelled engine that is used to draw trains along railway tracks
   
   
4. An instrument or machine that is used in warfare, such as a battering ram, catapult, artillery piece, etc.  ( engine )
   an instrument or machine that is used in warfare, such as a battering ram, catapult, artillery piece, etc.
    Medieval engines of war
   medieval engines of war