Definitions of incendiary:

• noun:   a bomb that is designed to start fires; are most effective against flammable targets (such as fuel)
• noun:   a criminal who illegally sets fire to property
• adjective:   arousing to action or rebellion
• adjective:   involving deliberate burning of property

  Example: "An incendiary fire"

• adjective:   capable of catching fire spontaneously or causing fires or burning readily

  Example: "An incendiary agent"