One who has committed the act of arson, or illegally setting fire to property.(noun)
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Use "arsonist" in a sentence
"A serial arsonist is at work in Mount Hope, many more people die, and Mulligan, having no faith in the city's incompetent police and crooked politicians, embarks on a personal crusade to find the killer."
"Having him as a leader of the panel would be like calling the arsonist to put out the fire."
"JOSEPH WAMBAUGH, AUTHOR, "FIRE LOVER": Well, originally it appeared that this guy's a disorganized serial arsonist, that is, an impulsive fire-setter who sets random fires, who's probably a nocturnal creature and a loner, and who doesn't plan for the severity of his crimes."