Causing or adapted to cause combustion; used in starting a fire or conflagration; igniting; inflammatory: as, incendiary materials; an incendiary match or bomb. SpecificallyPertaining or relating to or consisting in malicious or criminal setting on fire or burning: as, an incendiary mania; the incendiary torch; an incendiary fire.Tending to excite or inflame passion, sedition, or violence.n. A person who maliciously sets fire to a house, shop, barn, or other inflammable property; one who is guilty of arson.n. One who or that which excites or inflames; a person who excites antagonism and promotes factious quarrels; a violent agitator.