noun
Refers to a person who publicly supports or proposes an idea, theory, or cause.
彼は教育改革の提唱者として知られている。
He is known as a proponent of educational reform.
その理論の提唱者はまだ若い研
The advocate of that theory is still a young researcher.
支持者 is a supporter or backer, often in a more passive sense, while 提唱者 actively promotes or champions the idea.
Compound of 提唱 (advocacy, proposal) + 者 (person). 提唱 is from 提 (present, carry) and 唱 (chant, advocate).