The Collaborative International Dictionary of English v.0.48:

Incendiary \In*cen"di*a*ry\ (?; 277), n.; pl. Incendiaries.
   [L. incendiarius: cf. F. incendiaire. See Incense to
   inflame.]
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   1. Any person who maliciously sets fire to a building or
      other valuable or other valuable property.
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   2. A person who excites or inflames factions, and promotes
      quarrels or sedition; an agitator; an exciter.
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            Several cities . . . drove them out as incendiaries.
                                                  --Bentley.
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