OneLook Thesaurus

From the website:

OneLook helps you find words for any type of writing.

It's similar to a traditional thesaurus that finds synonyms and antonyms, but provides greater depth, variety, and flexibility.

Simply enter a single word or a few words; a phrase, description, or even a whole sentence to describe what you need and find related words, concepts, and more.

Free, the way we like it.