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.
Any number that contacts you is run through Hiya's database, and if there's a match, the app will automatically block the number; if there isn't a match, the call or text will go through.
Source: https://mashable.com/roundup/best-robocall-blocking-apps