Meaning of “fantastic” - Learner’s Dictionary

fantastic

adjective uk us /fænˈtæstɪk/
GOOD informal

A2 very good:

He looks fantastic in that suit.
I've had a fantastic time.
LARGE informal

A fantastic amount or number of something is very large:

They're making fantastic amounts of money.
STRANGE

very strange and probably not true:

fantastic stories about monsters and witches

(Definition of “fantastic” from the Cambridge Learner’s Dictionary © Cambridge University Press)