https://techcrunch.com/2018/11/05/reverso-launches-synonyms-app-and-service/

Language learning company Reverso is launching a new product on the web and mobile. Reverso Synonyms is a thesaurus service that lets you learn new words and improve your vocabulary.

You may have found this feature in the main Reverso translation app already. If you translate a word or a group of words, there’s a tiny “S” button in the corner. It lets you access related words directly from the translation app.