Proponent and opponent are easily confused words.
The spell-check application of most word processing software programs would not catch a slip-up of these two words. Spell-check is looking for words that aren’t in its dictionary, and words that resemble words in its dictionary, but are possibly spelled wrong. Spell-check isn’t perfect. It doesn’t know and can’t guess what word you wanted, or what word you meant, it can only judge the words on the page. If you used words that are all spelled correctly, it gives you a pass anyway.
Autocorrect suggests words that start with the same letters. It’s suggesting what word you may want to save time, but quite often, its suggestions are pretty off base. They don’t help you out, but they do make you laugh.
Proponent (pronounced “”proh-poh-nihnt”) is a noun. It means an advocate, someone who promotes a cause or a viewpoint. Lobbyists, for example, are paid to be proponents for industry interests in Washington, DC.
Opponent (pronounced “oh-poh-nihnt”) is a noun. It means someone who is competing against someone else in sport, business, or politics. It can also mean someone who doesn’t agree with someone else, and the reader is hearing from just one person’s point of view.
The following story uses both words correctly:
Prospero claimed he was a proponent for civil rights and fighting inequality. Oslo, his opponent, had plenty of examples that these claims didn’t hold up.