
Advocate
noun
ad·vo·cate | \ ˈad-və-kət , -ˌkāt \
1: one who pleads the cause of another
2: one who defends or maintains a cause or proposal
3: one who supports or promotes the interests of a cause or group
verb
1: to support or argue for (a cause, policy, etc.)
2: to act as advocate for someone or something
See also:
backer, champion, friend, gospeler, herald, protagonist,
supporter, true believer, white knight