An arsonist is someone who deliberately sets fire to property or other objects. The term 'an arsonist' can be broken down into three words: ABET (4 letters), FIREBUG (7 letters), and TORCH (5 letters). ABET means to encourage or assist someone in doing something wrong, such as setting a fire. FIREBUG is another term for an arsonist, referring to someone who starts fires. TORCH is a slang term for an incendiary device, which is an object used to start a fire.