What are the four synonyms of fantastic?

It's impossible to give you four exact synonyms for "fantastic" because its meaning is quite broad. It can mean:

* Excellent: Amazing, incredible, superb, brilliant

* Imaginative: Whimsical, surreal, magical, mythical

* Unbelievable: Unthinkable, extraordinary, astounding, remarkable

To get the best synonym, you need more context. What is "fantastic" describing?

For example:

* "That was a fantastic movie!" You might use "amazing" or "brilliant".

* "He had a fantastic idea for a new invention." You might use "creative" or "ingenious".

* "The party was fantastic!" You might use "wonderful" or "spectacular".