Synonyms that are in the dictionary are marked in green. Synonyms that are not in the dictionary are marked in red.
Antonyms that are in the dictionary are marked in green. Antonyms that are not in the dictionary are marked in red.
But while Reddit figures it all out, it seems as though the website's retirement of coins and awards will leave it entirely without a rewards system, unless you count upvoting.
Source: https://mashable.com/article/reddit-gold-coins-awards-system-remove