noun
Refers to a person who agrees with or supports a particular political or ideological group, often without being an official member. The term can carry a slightly negative nuance of passive agreement.
彼は党員ではないが、同調者として活動している。
He is not a party member, but he is active as a sympathizer.
その組織には多くの同調者
That organization has many sympathizers.
共感者 emphasizes emotional empathy or shared feeling, while 同調者 focuses on agreement with a group's stance or ideology.
Compound of 同調 (dōchō, 'agreement; conformity') + 者 (sha, 'person'). The derivation is straightforward from the component kanji meanings.