The difference between Opponent and Proponent

When used as nouns, opponent means one who opposes another, whereas proponent means one who supports something.

When used as adjectives, opponent means opposing, whereas proponent means making proposals.

check bellow for the other definitions of Opponent and Proponent

Opponent as a noun (historical):

One who opposes another; one who works or takes a position against someone or something; one who attempts to stop the progress of someone or something. One who opposes another physically (in a fight, sport, game, or competition). One who opposes another in words (in a dispute, argument or controversy). One who is opposed or objects (to a policy, course of action or set of ideas). The participant who opens an academic debate by putting forward objections to a theological or philosophical thesis.

Examples:

"The person who ran against her in the last election proved to be a formidable opponent."

"During the crackdown, many opponents of the regime were arrested."

"She was a dedicated opponent of the death penalty."

Opponent as an adjective (obsolete):

Opposing; adverse; antagonistic.
Opponent as an adjective (obsolete):

Situated in front; opposite.