arson; arsonist
Refers both to the crime of arson and to a person who commits arson. Context determines whether it means the act or the perpetrator.
The police arrested a man on suspicion of arson.
The fire is believed to be the work of an arsonist.
Compound of 放火 (ほうか, 'arson') and 犯 (はん, 'crime' or 'criminal').