The definition of an enthusiast is a person who is very excited about some person or thing.
The definition of an advocate is someone who fights for something or someone, especially someone who fights for the rights of others.
The definition of a champion is a person who is the best in his field or who has defeated all rivals.
A hostile power or force, such as a nation.
A personal enemy or opponent.
One that opposes another or others, as in a battle, contest, or debate:
Find another word for proponent. In this page you can discover 16 synonyms, antonyms, idiomatic expressions, and related words for proponent, like: proposer, theorist, enemy, protector, exponent, tenet, advocator, defender, booster, ideologue and sceptic.