(1):

(a.) Tending to excite or inflame factions, sedition, or quarrel; inflammatory; seditious.

(2):

(a.) Of or pertaining to incendiarism, or the malicious burning of valuable property; as, incendiary material; as incendiary crime.

(3):

(n.) A person who excites or inflames factions, and promotes quarrels or sedition; an agitator; an exciter.

(4):

(n.) Any person who maliciously sets fire to a building or other valuable or other valuable property.