backer
/ˈbækə(r)/noun
1- a person, institution, or country that supports someone or something, especially financially支持者; 赞助者：
a struggle to find a new financial backer.
为寻找新的资金赞助者所做的努力。
1.1
- a person that bets on a horse（赛马的）下（赌）注者。