Refers to a person who stirs up public feeling, often for political ends. Can be used neutrally or pejoratively.
He is a demagogue who stirs up the masses with skillful speeches.
その扇動家はデモ隊を先導した。
The agitator led the group of demonstrators.
Standard kanji spelling using 扇 (fan/instigate).
Variant using 煽 (fan/agitate), also common.
Compound of 扇動 (incitement, agitation) and 家 (person, specialist). The kanji 扇 means 'fan' and metaphorically 'to stir up'.