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.
The feature was previously available in the Facebook app, but the company moved chats to the standalone messenger app in 2014.
To start, open up your Facebook app on a mobile device or go directly to www.facebook.com on a desktop computer.
Source: https://www.devicemag.com/how-to-change-the-language-on-facebook/