Fantastic means extraordinarily good, impressive, or wonderful. When your teacher says you did a fantastic job on your science project, she means it was excellent, maybe even beyond what she expected. A fantastic vacation might include perfect weather, exciting adventures, and memories you'll treasure for years.

The word carries a sense of delight and enthusiasm. It's stronger than just “good” or “nice.” A fantastic soccer goal is one that makes the whole crowd gasp, perhaps because of an incredible kick or clever teamwork. A fantastic book is one you can't put down, that makes you laugh or think or feel deeply moved.

You can also use fantastic for things that seem almost too wonderful or strange to be real, like a fantastic creature such as a dragon, or an excuse that sounds too fantastic to be believed. But most of the time today, people use it simply to express genuine excitement and approval about something truly excellent.